* [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 16:41 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-22 16:41 UTC (permalink / raw) To: Eric Engestrom Cc: David Airlie, DRI devel, LKML, Rob Clark, Jani Nikula, Daniel Vetter drm_get_format_name() de-references the buf parameter without checking if the pointer was not NULL. Given that the function is EXPORT-ed, lets sanitise the parameters before proceeding. Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) Cc: Eric Engestrom <eric@engestrom.ch> Cc: Rob Clark <robdclark@gmail.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> --- drivers/gpu/drm/drm_fourcc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index 90d2cc8..0a3ff0b 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); */ const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) { + if (!buf) + return NULL; + snprintf(buf->str, sizeof(buf->str), "%c%c%c%c %s-endian (0x%08x)", printable_char(format & 0xff), -- 2.10.2 ^ permalink raw reply related [flat|nested] 32+ messages in thread
* [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 16:41 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-22 16:41 UTC (permalink / raw) To: Eric Engestrom; +Cc: Daniel Vetter, LKML, DRI devel, Jani Nikula drm_get_format_name() de-references the buf parameter without checking if the pointer was not NULL. Given that the function is EXPORT-ed, lets sanitise the parameters before proceeding. Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) Cc: Eric Engestrom <eric@engestrom.ch> Cc: Rob Clark <robdclark@gmail.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> --- drivers/gpu/drm/drm_fourcc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index 90d2cc8..0a3ff0b 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); */ const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) { + if (!buf) + return NULL; + snprintf(buf->str, sizeof(buf->str), "%c%c%c%c %s-endian (0x%08x)", printable_char(format & 0xff), -- 2.10.2 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply related [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 16:41 ` Liviu Dudau @ 2016-11-22 16:50 ` Ville Syrjälä -1 siblings, 0 replies; 32+ messages in thread From: Ville Syrjälä @ 2016-11-22 16:50 UTC (permalink / raw) To: Liviu Dudau; +Cc: Eric Engestrom, Daniel Vetter, LKML, DRI devel, Jani Nikula On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > drm_get_format_name() de-references the buf parameter without checking > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > sanitise the parameters before proceeding. > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > Cc: Eric Engestrom <eric@engestrom.ch> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Jani Nikula <jani.nikula@intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > --- > drivers/gpu/drm/drm_fourcc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index 90d2cc8..0a3ff0b 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > */ > const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > { > + if (!buf) > + return NULL; > + Seems rather pointless to me. Why would you ever pass NULL to this guy? > snprintf(buf->str, sizeof(buf->str), > "%c%c%c%c %s-endian (0x%08x)", > printable_char(format & 0xff), > -- > 2.10.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel OTC ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 16:50 ` Ville Syrjälä 0 siblings, 0 replies; 32+ messages in thread From: Ville Syrjälä @ 2016-11-22 16:50 UTC (permalink / raw) To: Liviu Dudau; +Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > drm_get_format_name() de-references the buf parameter without checking > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > sanitise the parameters before proceeding. > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > Cc: Eric Engestrom <eric@engestrom.ch> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Jani Nikula <jani.nikula@intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > --- > drivers/gpu/drm/drm_fourcc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index 90d2cc8..0a3ff0b 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > */ > const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > { > + if (!buf) > + return NULL; > + Seems rather pointless to me. Why would you ever pass NULL to this guy? > snprintf(buf->str, sizeof(buf->str), > "%c%c%c%c %s-endian (0x%08x)", > printable_char(format & 0xff), > -- > 2.10.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 16:50 ` Ville Syrjälä @ 2016-11-22 17:23 ` Rob Clark -1 siblings, 0 replies; 32+ messages in thread From: Rob Clark @ 2016-11-22 17:23 UTC (permalink / raw) To: Ville Syrjälä Cc: Liviu Dudau, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> drm_get_format_name() de-references the buf parameter without checking >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> sanitise the parameters before proceeding. >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> Cc: Eric Engestrom <eric@engestrom.ch> >> Cc: Rob Clark <robdclark@gmail.com> >> Cc: Jani Nikula <jani.nikula@intel.com> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> --- >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> index 90d2cc8..0a3ff0b 100644 >> --- a/drivers/gpu/drm/drm_fourcc.c >> +++ b/drivers/gpu/drm/drm_fourcc.c >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> */ >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> { >> + if (!buf) >> + return NULL; >> + > > Seems rather pointless to me. Why would you ever pass NULL to this guy? perhaps BUG_ON(!buf)... BR, -R >> snprintf(buf->str, sizeof(buf->str), >> "%c%c%c%c %s-endian (0x%08x)", >> printable_char(format & 0xff), >> -- >> 2.10.2 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel OTC > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 17:23 ` Rob Clark 0 siblings, 0 replies; 32+ messages in thread From: Rob Clark @ 2016-11-22 17:23 UTC (permalink / raw) To: Ville Syrjälä Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, Liviu Dudau, LKML, DRI devel On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> drm_get_format_name() de-references the buf parameter without checking >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> sanitise the parameters before proceeding. >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> Cc: Eric Engestrom <eric@engestrom.ch> >> Cc: Rob Clark <robdclark@gmail.com> >> Cc: Jani Nikula <jani.nikula@intel.com> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> --- >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> index 90d2cc8..0a3ff0b 100644 >> --- a/drivers/gpu/drm/drm_fourcc.c >> +++ b/drivers/gpu/drm/drm_fourcc.c >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> */ >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> { >> + if (!buf) >> + return NULL; >> + > > Seems rather pointless to me. Why would you ever pass NULL to this guy? perhaps BUG_ON(!buf)... BR, -R >> snprintf(buf->str, sizeof(buf->str), >> "%c%c%c%c %s-endian (0x%08x)", >> printable_char(format & 0xff), >> -- >> 2.10.2 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel OTC > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 17:23 ` Rob Clark @ 2016-11-22 17:31 ` Ville Syrjälä -1 siblings, 0 replies; 32+ messages in thread From: Ville Syrjälä @ 2016-11-22 17:31 UTC (permalink / raw) To: Rob Clark Cc: Liviu Dudau, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> drm_get_format_name() de-references the buf parameter without checking > >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> sanitise the parameters before proceeding. > >> > >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> Cc: Eric Engestrom <eric@engestrom.ch> > >> Cc: Rob Clark <robdclark@gmail.com> > >> Cc: Jani Nikula <jani.nikula@intel.com> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> > >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> --- > >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> index 90d2cc8..0a3ff0b 100644 > >> --- a/drivers/gpu/drm/drm_fourcc.c > >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> */ > >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> { > >> + if (!buf) > >> + return NULL; > >> + > > > > Seems rather pointless to me. Why would you ever pass NULL to this guy? > > perhaps BUG_ON(!buf)... And how does that differ from just buf->foo? > > BR, > -R > > >> snprintf(buf->str, sizeof(buf->str), > >> "%c%c%c%c %s-endian (0x%08x)", > >> printable_char(format & 0xff), > >> -- > >> 2.10.2 > >> > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@lists.freedesktop.org > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > > Ville Syrjälä > > Intel OTC > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel OTC ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 17:31 ` Ville Syrjälä 0 siblings, 0 replies; 32+ messages in thread From: Ville Syrjälä @ 2016-11-22 17:31 UTC (permalink / raw) To: Rob Clark Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, Liviu Dudau, LKML, DRI devel On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> drm_get_format_name() de-references the buf parameter without checking > >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> sanitise the parameters before proceeding. > >> > >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> Cc: Eric Engestrom <eric@engestrom.ch> > >> Cc: Rob Clark <robdclark@gmail.com> > >> Cc: Jani Nikula <jani.nikula@intel.com> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> > >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> --- > >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> index 90d2cc8..0a3ff0b 100644 > >> --- a/drivers/gpu/drm/drm_fourcc.c > >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> */ > >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> { > >> + if (!buf) > >> + return NULL; > >> + > > > > Seems rather pointless to me. Why would you ever pass NULL to this guy? > > perhaps BUG_ON(!buf)... And how does that differ from just buf->foo? > > BR, > -R > > >> snprintf(buf->str, sizeof(buf->str), > >> "%c%c%c%c %s-endian (0x%08x)", > >> printable_char(format & 0xff), > >> -- > >> 2.10.2 > >> > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@lists.freedesktop.org > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > > Ville Syrjälä > > Intel OTC > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 17:31 ` Ville Syrjälä @ 2016-11-22 17:35 ` Rob Clark -1 siblings, 0 replies; 32+ messages in thread From: Rob Clark @ 2016-11-22 17:35 UTC (permalink / raw) To: Ville Syrjälä Cc: Liviu Dudau, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä >> <ville.syrjala@linux.intel.com> wrote: >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> >> drm_get_format_name() de-references the buf parameter without checking >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> >> sanitise the parameters before proceeding. >> >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> >> Cc: Eric Engestrom <eric@engestrom.ch> >> >> Cc: Rob Clark <robdclark@gmail.com> >> >> Cc: Jani Nikula <jani.nikula@intel.com> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> >> --- >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> >> 1 file changed, 3 insertions(+) >> >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> >> index 90d2cc8..0a3ff0b 100644 >> >> --- a/drivers/gpu/drm/drm_fourcc.c >> >> +++ b/drivers/gpu/drm/drm_fourcc.c >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> >> */ >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> >> { >> >> + if (!buf) >> >> + return NULL; >> >> + >> > >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? >> >> perhaps BUG_ON(!buf)... > > And how does that differ from just buf->foo? it gets you a file and line # in the error splat.. not that drm_get_format_name() is such a big function that it would be difficult to decipher the null deref crash, but if we added anything it should be BUG_ON() to make it clear that passing null isn't a caller error. BR, -R >> >> BR, >> -R >> >> >> snprintf(buf->str, sizeof(buf->str), >> >> "%c%c%c%c %s-endian (0x%08x)", >> >> printable_char(format & 0xff), >> >> -- >> >> 2.10.2 >> >> >> >> _______________________________________________ >> >> dri-devel mailing list >> >> dri-devel@lists.freedesktop.org >> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >> > >> > -- >> > Ville Syrjälä >> > Intel OTC >> > _______________________________________________ >> > dri-devel mailing list >> > dri-devel@lists.freedesktop.org >> > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel OTC ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 17:35 ` Rob Clark 0 siblings, 0 replies; 32+ messages in thread From: Rob Clark @ 2016-11-22 17:35 UTC (permalink / raw) To: Ville Syrjälä Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, Liviu Dudau, LKML, DRI devel On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä >> <ville.syrjala@linux.intel.com> wrote: >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> >> drm_get_format_name() de-references the buf parameter without checking >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> >> sanitise the parameters before proceeding. >> >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> >> Cc: Eric Engestrom <eric@engestrom.ch> >> >> Cc: Rob Clark <robdclark@gmail.com> >> >> Cc: Jani Nikula <jani.nikula@intel.com> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> >> --- >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> >> 1 file changed, 3 insertions(+) >> >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> >> index 90d2cc8..0a3ff0b 100644 >> >> --- a/drivers/gpu/drm/drm_fourcc.c >> >> +++ b/drivers/gpu/drm/drm_fourcc.c >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> >> */ >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> >> { >> >> + if (!buf) >> >> + return NULL; >> >> + >> > >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? >> >> perhaps BUG_ON(!buf)... > > And how does that differ from just buf->foo? it gets you a file and line # in the error splat.. not that drm_get_format_name() is such a big function that it would be difficult to decipher the null deref crash, but if we added anything it should be BUG_ON() to make it clear that passing null isn't a caller error. BR, -R >> >> BR, >> -R >> >> >> snprintf(buf->str, sizeof(buf->str), >> >> "%c%c%c%c %s-endian (0x%08x)", >> >> printable_char(format & 0xff), >> >> -- >> >> 2.10.2 >> >> >> >> _______________________________________________ >> >> dri-devel mailing list >> >> dri-devel@lists.freedesktop.org >> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >> > >> > -- >> > Ville Syrjälä >> > Intel OTC >> > _______________________________________________ >> > dri-devel mailing list >> > dri-devel@lists.freedesktop.org >> > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel OTC _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 17:35 ` Rob Clark @ 2016-11-22 18:06 ` Ville Syrjälä -1 siblings, 0 replies; 32+ messages in thread From: Ville Syrjälä @ 2016-11-22 18:06 UTC (permalink / raw) To: Rob Clark Cc: Liviu Dudau, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: > On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > >> <ville.syrjala@linux.intel.com> wrote: > >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> >> drm_get_format_name() de-references the buf parameter without checking > >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> >> sanitise the parameters before proceeding. > >> >> > >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> >> Cc: Eric Engestrom <eric@engestrom.ch> > >> >> Cc: Rob Clark <robdclark@gmail.com> > >> >> Cc: Jani Nikula <jani.nikula@intel.com> > >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> >> > >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> >> --- > >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> >> 1 file changed, 3 insertions(+) > >> >> > >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> >> index 90d2cc8..0a3ff0b 100644 > >> >> --- a/drivers/gpu/drm/drm_fourcc.c > >> >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> >> */ > >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> >> { > >> >> + if (!buf) > >> >> + return NULL; > >> >> + > >> > > >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? > >> > >> perhaps BUG_ON(!buf)... > > > > And how does that differ from just buf->foo? > > it gets you a file and line # in the error splat.. not that > drm_get_format_name() is such a big function that it would be > difficult to decipher the null deref crash, but if we added anything > it should be BUG_ON() to make it clear that passing null isn't a > caller error. Yeah, BUG_ON() at least documents the intent, so it's better than the null check. But for something like this even BUG_ON() is just wasted bytes IMO. BUG_ON() can be useful for those weird bugs where somewhere deep down you hit a null pointer and you can't figure out where the bad pointer came from. So you might sprinkle a few BUG_ONs() further up to catch it sooner. Esp. if you can't reproduce the bug yourself and have to rely on user(s) to find it for you. Even WARN_ON() w/ or w/o an early bailout might be a decent idea sometimes since it might have a slightly higher chance of keeping the kernel in working condition, but IMO just blindly throwing it around everywhere is not a good approach. -- Ville Syrjälä Intel OTC ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 18:06 ` Ville Syrjälä 0 siblings, 0 replies; 32+ messages in thread From: Ville Syrjälä @ 2016-11-22 18:06 UTC (permalink / raw) To: Rob Clark Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, Liviu Dudau, LKML, DRI devel On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: > On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > >> <ville.syrjala@linux.intel.com> wrote: > >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> >> drm_get_format_name() de-references the buf parameter without checking > >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> >> sanitise the parameters before proceeding. > >> >> > >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> >> Cc: Eric Engestrom <eric@engestrom.ch> > >> >> Cc: Rob Clark <robdclark@gmail.com> > >> >> Cc: Jani Nikula <jani.nikula@intel.com> > >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> >> > >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> >> --- > >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> >> 1 file changed, 3 insertions(+) > >> >> > >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> >> index 90d2cc8..0a3ff0b 100644 > >> >> --- a/drivers/gpu/drm/drm_fourcc.c > >> >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> >> */ > >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> >> { > >> >> + if (!buf) > >> >> + return NULL; > >> >> + > >> > > >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? > >> > >> perhaps BUG_ON(!buf)... > > > > And how does that differ from just buf->foo? > > it gets you a file and line # in the error splat.. not that > drm_get_format_name() is such a big function that it would be > difficult to decipher the null deref crash, but if we added anything > it should be BUG_ON() to make it clear that passing null isn't a > caller error. Yeah, BUG_ON() at least documents the intent, so it's better than the null check. But for something like this even BUG_ON() is just wasted bytes IMO. BUG_ON() can be useful for those weird bugs where somewhere deep down you hit a null pointer and you can't figure out where the bad pointer came from. So you might sprinkle a few BUG_ONs() further up to catch it sooner. Esp. if you can't reproduce the bug yourself and have to rely on user(s) to find it for you. Even WARN_ON() w/ or w/o an early bailout might be a decent idea sometimes since it might have a slightly higher chance of keeping the kernel in working condition, but IMO just blindly throwing it around everywhere is not a good approach. -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 18:06 ` Ville Syrjälä @ 2016-11-22 18:15 ` Sean Paul -1 siblings, 0 replies; 32+ messages in thread From: Sean Paul @ 2016-11-22 18:15 UTC (permalink / raw) To: Ville Syrjälä Cc: Rob Clark, Jani Nikula, Daniel Vetter, Eric Engestrom, Liviu Dudau, LKML, DRI devel On Tue, Nov 22, 2016 at 1:06 PM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: > On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: >> On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä >> <ville.syrjala@linux.intel.com> wrote: >> > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: >> >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä >> >> <ville.syrjala@linux.intel.com> wrote: >> >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> >> >> drm_get_format_name() de-references the buf parameter without checking >> >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> >> >> sanitise the parameters before proceeding. >> >> >> >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> >> >> Cc: Eric Engestrom <eric@engestrom.ch> >> >> >> Cc: Rob Clark <robdclark@gmail.com> >> >> >> Cc: Jani Nikula <jani.nikula@intel.com> >> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> >> >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> >> >> --- >> >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> >> >> 1 file changed, 3 insertions(+) >> >> >> >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> >> >> index 90d2cc8..0a3ff0b 100644 >> >> >> --- a/drivers/gpu/drm/drm_fourcc.c >> >> >> +++ b/drivers/gpu/drm/drm_fourcc.c >> >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> >> >> */ >> >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> >> >> { >> >> >> + if (!buf) >> >> >> + return NULL; >> >> >> + >> >> > >> >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? >> >> >> >> perhaps BUG_ON(!buf)... >> > >> > And how does that differ from just buf->foo? >> >> it gets you a file and line # in the error splat.. not that >> drm_get_format_name() is such a big function that it would be >> difficult to decipher the null deref crash, but if we added anything >> it should be BUG_ON() to make it clear that passing null isn't a >> caller error. > > Yeah, BUG_ON() at least documents the intent, so it's better than > the null check. But for something like this even BUG_ON() is > just wasted bytes IMO. +1 The patch has a Fixes line, but AFAICT, the referenced patch didn't introduce any NULL opportunities that weren't previously there. Sean > > BUG_ON() can be useful for those weird bugs where somewhere deep > down you hit a null pointer and you can't figure out where the > bad pointer came from. So you might sprinkle a few BUG_ONs() > further up to catch it sooner. Esp. if you can't reproduce the > bug yourself and have to rely on user(s) to find it for you. > > Even WARN_ON() w/ or w/o an early bailout might be a decent idea > sometimes since it might have a slightly higher chance of keeping > the kernel in working condition, but IMO just blindly throwing > it around everywhere is not a good approach. > > -- > Ville Syrjälä > Intel OTC > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 18:15 ` Sean Paul 0 siblings, 0 replies; 32+ messages in thread From: Sean Paul @ 2016-11-22 18:15 UTC (permalink / raw) To: Ville Syrjälä Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, Liviu Dudau, LKML, DRI devel On Tue, Nov 22, 2016 at 1:06 PM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: > On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: >> On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä >> <ville.syrjala@linux.intel.com> wrote: >> > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: >> >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä >> >> <ville.syrjala@linux.intel.com> wrote: >> >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> >> >> drm_get_format_name() de-references the buf parameter without checking >> >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> >> >> sanitise the parameters before proceeding. >> >> >> >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> >> >> Cc: Eric Engestrom <eric@engestrom.ch> >> >> >> Cc: Rob Clark <robdclark@gmail.com> >> >> >> Cc: Jani Nikula <jani.nikula@intel.com> >> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> >> >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> >> >> --- >> >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> >> >> 1 file changed, 3 insertions(+) >> >> >> >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> >> >> index 90d2cc8..0a3ff0b 100644 >> >> >> --- a/drivers/gpu/drm/drm_fourcc.c >> >> >> +++ b/drivers/gpu/drm/drm_fourcc.c >> >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> >> >> */ >> >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> >> >> { >> >> >> + if (!buf) >> >> >> + return NULL; >> >> >> + >> >> > >> >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? >> >> >> >> perhaps BUG_ON(!buf)... >> > >> > And how does that differ from just buf->foo? >> >> it gets you a file and line # in the error splat.. not that >> drm_get_format_name() is such a big function that it would be >> difficult to decipher the null deref crash, but if we added anything >> it should be BUG_ON() to make it clear that passing null isn't a >> caller error. > > Yeah, BUG_ON() at least documents the intent, so it's better than > the null check. But for something like this even BUG_ON() is > just wasted bytes IMO. +1 The patch has a Fixes line, but AFAICT, the referenced patch didn't introduce any NULL opportunities that weren't previously there. Sean > > BUG_ON() can be useful for those weird bugs where somewhere deep > down you hit a null pointer and you can't figure out where the > bad pointer came from. So you might sprinkle a few BUG_ONs() > further up to catch it sooner. Esp. if you can't reproduce the > bug yourself and have to rely on user(s) to find it for you. > > Even WARN_ON() w/ or w/o an early bailout might be a decent idea > sometimes since it might have a slightly higher chance of keeping > the kernel in working condition, but IMO just blindly throwing > it around everywhere is not a good approach. > > -- > Ville Syrjälä > Intel OTC > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 18:15 ` Sean Paul @ 2016-11-22 18:47 ` Liviu Dudau -1 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-22 18:47 UTC (permalink / raw) To: Sean Paul Cc: Ville Syrjälä, Rob Clark, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 01:15:08PM -0500, Sean Paul wrote: > On Tue, Nov 22, 2016 at 1:06 PM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: > >> On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä > >> <ville.syrjala@linux.intel.com> wrote: > >> > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > >> >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > >> >> <ville.syrjala@linux.intel.com> wrote: > >> >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> >> >> drm_get_format_name() de-references the buf parameter without checking > >> >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> >> >> sanitise the parameters before proceeding. > >> >> >> > >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> >> >> Cc: Eric Engestrom <eric@engestrom.ch> > >> >> >> Cc: Rob Clark <robdclark@gmail.com> > >> >> >> Cc: Jani Nikula <jani.nikula@intel.com> > >> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> >> >> > >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> >> >> --- > >> >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> >> >> 1 file changed, 3 insertions(+) > >> >> >> > >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> >> >> index 90d2cc8..0a3ff0b 100644 > >> >> >> --- a/drivers/gpu/drm/drm_fourcc.c > >> >> >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> >> >> */ > >> >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> >> >> { > >> >> >> + if (!buf) > >> >> >> + return NULL; > >> >> >> + > >> >> > > >> >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? I don't know, maybe because I'm a malicious driver writer that wants to crash the kernel? The function is exported, so it can be called by any module, even out-of-tree. Looks like an easy DoS to me. > >> >> > >> >> perhaps BUG_ON(!buf)... > >> > > >> > And how does that differ from just buf->foo? > >> > >> it gets you a file and line # in the error splat.. not that > >> drm_get_format_name() is such a big function that it would be > >> difficult to decipher the null deref crash, but if we added anything > >> it should be BUG_ON() to make it clear that passing null isn't a > >> caller error. > > > > Yeah, BUG_ON() at least documents the intent, so it's better than > > the null check. But for something like this even BUG_ON() is > > just wasted bytes IMO. > > +1 > > The patch has a Fixes line, but AFAICT, the referenced patch didn't > introduce any NULL opportunities that weren't previously there. Really? Before the referenced patch the function only had one parameter, an uint32_t. True that kmalloc could return a NULL pointer and we would've crashed there as well, but at least we were running out of memory. Now I can crash the kernel any time I want with a badly written driver/module. Best regards, Liviu > > Sean > > > > > > BUG_ON() can be useful for those weird bugs where somewhere deep > > down you hit a null pointer and you can't figure out where the > > bad pointer came from. So you might sprinkle a few BUG_ONs() > > further up to catch it sooner. Esp. if you can't reproduce the > > bug yourself and have to rely on user(s) to find it for you. > > > > Even WARN_ON() w/ or w/o an early bailout might be a decent idea > > sometimes since it might have a slightly higher chance of keeping > > the kernel in working condition, but IMO just blindly throwing > > it around everywhere is not a good approach. > > > > -- > > Ville Syrjälä > > Intel OTC > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 18:47 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-22 18:47 UTC (permalink / raw) To: Sean Paul; +Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 01:15:08PM -0500, Sean Paul wrote: > On Tue, Nov 22, 2016 at 1:06 PM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: > >> On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä > >> <ville.syrjala@linux.intel.com> wrote: > >> > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > >> >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > >> >> <ville.syrjala@linux.intel.com> wrote: > >> >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> >> >> drm_get_format_name() de-references the buf parameter without checking > >> >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> >> >> sanitise the parameters before proceeding. > >> >> >> > >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> >> >> Cc: Eric Engestrom <eric@engestrom.ch> > >> >> >> Cc: Rob Clark <robdclark@gmail.com> > >> >> >> Cc: Jani Nikula <jani.nikula@intel.com> > >> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> >> >> > >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> >> >> --- > >> >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> >> >> 1 file changed, 3 insertions(+) > >> >> >> > >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> >> >> index 90d2cc8..0a3ff0b 100644 > >> >> >> --- a/drivers/gpu/drm/drm_fourcc.c > >> >> >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> >> >> */ > >> >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> >> >> { > >> >> >> + if (!buf) > >> >> >> + return NULL; > >> >> >> + > >> >> > > >> >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? I don't know, maybe because I'm a malicious driver writer that wants to crash the kernel? The function is exported, so it can be called by any module, even out-of-tree. Looks like an easy DoS to me. > >> >> > >> >> perhaps BUG_ON(!buf)... > >> > > >> > And how does that differ from just buf->foo? > >> > >> it gets you a file and line # in the error splat.. not that > >> drm_get_format_name() is such a big function that it would be > >> difficult to decipher the null deref crash, but if we added anything > >> it should be BUG_ON() to make it clear that passing null isn't a > >> caller error. > > > > Yeah, BUG_ON() at least documents the intent, so it's better than > > the null check. But for something like this even BUG_ON() is > > just wasted bytes IMO. > > +1 > > The patch has a Fixes line, but AFAICT, the referenced patch didn't > introduce any NULL opportunities that weren't previously there. Really? Before the referenced patch the function only had one parameter, an uint32_t. True that kmalloc could return a NULL pointer and we would've crashed there as well, but at least we were running out of memory. Now I can crash the kernel any time I want with a badly written driver/module. Best regards, Liviu > > Sean > > > > > > BUG_ON() can be useful for those weird bugs where somewhere deep > > down you hit a null pointer and you can't figure out where the > > bad pointer came from. So you might sprinkle a few BUG_ONs() > > further up to catch it sooner. Esp. if you can't reproduce the > > bug yourself and have to rely on user(s) to find it for you. > > > > Even WARN_ON() w/ or w/o an early bailout might be a decent idea > > sometimes since it might have a slightly higher chance of keeping > > the kernel in working condition, but IMO just blindly throwing > > it around everywhere is not a good approach. > > > > -- > > Ville Syrjälä > > Intel OTC > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 18:47 ` Liviu Dudau @ 2016-11-22 21:46 ` Rob Clark -1 siblings, 0 replies; 32+ messages in thread From: Rob Clark @ 2016-11-22 21:46 UTC (permalink / raw) To: Liviu Dudau Cc: Sean Paul, Ville Syrjälä, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 1:47 PM, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > On Tue, Nov 22, 2016 at 01:15:08PM -0500, Sean Paul wrote: >> On Tue, Nov 22, 2016 at 1:06 PM, Ville Syrjälä >> <ville.syrjala@linux.intel.com> wrote: >> > On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: >> >> On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä >> >> <ville.syrjala@linux.intel.com> wrote: >> >> > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: >> >> >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä >> >> >> <ville.syrjala@linux.intel.com> wrote: >> >> >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> >> >> >> drm_get_format_name() de-references the buf parameter without checking >> >> >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> >> >> >> sanitise the parameters before proceeding. >> >> >> >> >> >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> >> >> >> Cc: Eric Engestrom <eric@engestrom.ch> >> >> >> >> Cc: Rob Clark <robdclark@gmail.com> >> >> >> >> Cc: Jani Nikula <jani.nikula@intel.com> >> >> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> >> >> >> >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> >> >> >> --- >> >> >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> >> >> >> 1 file changed, 3 insertions(+) >> >> >> >> >> >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> >> >> >> index 90d2cc8..0a3ff0b 100644 >> >> >> >> --- a/drivers/gpu/drm/drm_fourcc.c >> >> >> >> +++ b/drivers/gpu/drm/drm_fourcc.c >> >> >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> >> >> >> */ >> >> >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> >> >> >> { >> >> >> >> + if (!buf) >> >> >> >> + return NULL; >> >> >> >> + >> >> >> > >> >> >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? > > I don't know, maybe because I'm a malicious driver writer that wants to crash the kernel? > The function is exported, so it can be called by any module, even out-of-tree. Looks > like an easy DoS to me. if you are a kernel module, in tree or not, all bets are off.. an out of tree module could just as easily call sprintf(NULL, "foo") directly.. BR, -R >> >> >> >> >> >> perhaps BUG_ON(!buf)... >> >> > >> >> > And how does that differ from just buf->foo? >> >> >> >> it gets you a file and line # in the error splat.. not that >> >> drm_get_format_name() is such a big function that it would be >> >> difficult to decipher the null deref crash, but if we added anything >> >> it should be BUG_ON() to make it clear that passing null isn't a >> >> caller error. >> > >> > Yeah, BUG_ON() at least documents the intent, so it's better than >> > the null check. But for something like this even BUG_ON() is >> > just wasted bytes IMO. >> >> +1 >> >> The patch has a Fixes line, but AFAICT, the referenced patch didn't >> introduce any NULL opportunities that weren't previously there. > > Really? Before the referenced patch the function only had one parameter, > an uint32_t. True that kmalloc could return a NULL pointer and we would've > crashed there as well, but at least we were running out of memory. Now > I can crash the kernel any time I want with a badly written driver/module. > > Best regards, > Liviu > >> >> Sean >> >> >> > >> > BUG_ON() can be useful for those weird bugs where somewhere deep >> > down you hit a null pointer and you can't figure out where the >> > bad pointer came from. So you might sprinkle a few BUG_ONs() >> > further up to catch it sooner. Esp. if you can't reproduce the >> > bug yourself and have to rely on user(s) to find it for you. >> > >> > Even WARN_ON() w/ or w/o an early bailout might be a decent idea >> > sometimes since it might have a slightly higher chance of keeping >> > the kernel in working condition, but IMO just blindly throwing >> > it around everywhere is not a good approach. >> > >> > -- >> > Ville Syrjälä >> > Intel OTC >> > _______________________________________________ >> > dri-devel mailing list >> > dri-devel@lists.freedesktop.org >> > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > ==================== > | I would like to | > | fix the world, | > | but they're not | > | giving me the | > \ source code! / > --------------- > ¯\_(ツ)_/¯ ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 21:46 ` Rob Clark 0 siblings, 0 replies; 32+ messages in thread From: Rob Clark @ 2016-11-22 21:46 UTC (permalink / raw) To: Liviu Dudau; +Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 1:47 PM, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > On Tue, Nov 22, 2016 at 01:15:08PM -0500, Sean Paul wrote: >> On Tue, Nov 22, 2016 at 1:06 PM, Ville Syrjälä >> <ville.syrjala@linux.intel.com> wrote: >> > On Tue, Nov 22, 2016 at 12:35:53PM -0500, Rob Clark wrote: >> >> On Tue, Nov 22, 2016 at 12:31 PM, Ville Syrjälä >> >> <ville.syrjala@linux.intel.com> wrote: >> >> > On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: >> >> >> On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä >> >> >> <ville.syrjala@linux.intel.com> wrote: >> >> >> > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: >> >> >> >> drm_get_format_name() de-references the buf parameter without checking >> >> >> >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> >> >> >> sanitise the parameters before proceeding. >> >> >> >> >> >> >> >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> >> >> >> Cc: Eric Engestrom <eric@engestrom.ch> >> >> >> >> Cc: Rob Clark <robdclark@gmail.com> >> >> >> >> Cc: Jani Nikula <jani.nikula@intel.com> >> >> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> >> >> >> >> >> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> >> >> >> --- >> >> >> >> drivers/gpu/drm/drm_fourcc.c | 3 +++ >> >> >> >> 1 file changed, 3 insertions(+) >> >> >> >> >> >> >> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c >> >> >> >> index 90d2cc8..0a3ff0b 100644 >> >> >> >> --- a/drivers/gpu/drm/drm_fourcc.c >> >> >> >> +++ b/drivers/gpu/drm/drm_fourcc.c >> >> >> >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); >> >> >> >> */ >> >> >> >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) >> >> >> >> { >> >> >> >> + if (!buf) >> >> >> >> + return NULL; >> >> >> >> + >> >> >> > >> >> >> > Seems rather pointless to me. Why would you ever pass NULL to this guy? > > I don't know, maybe because I'm a malicious driver writer that wants to crash the kernel? > The function is exported, so it can be called by any module, even out-of-tree. Looks > like an easy DoS to me. if you are a kernel module, in tree or not, all bets are off.. an out of tree module could just as easily call sprintf(NULL, "foo") directly.. BR, -R >> >> >> >> >> >> perhaps BUG_ON(!buf)... >> >> > >> >> > And how does that differ from just buf->foo? >> >> >> >> it gets you a file and line # in the error splat.. not that >> >> drm_get_format_name() is such a big function that it would be >> >> difficult to decipher the null deref crash, but if we added anything >> >> it should be BUG_ON() to make it clear that passing null isn't a >> >> caller error. >> > >> > Yeah, BUG_ON() at least documents the intent, so it's better than >> > the null check. But for something like this even BUG_ON() is >> > just wasted bytes IMO. >> >> +1 >> >> The patch has a Fixes line, but AFAICT, the referenced patch didn't >> introduce any NULL opportunities that weren't previously there. > > Really? Before the referenced patch the function only had one parameter, > an uint32_t. True that kmalloc could return a NULL pointer and we would've > crashed there as well, but at least we were running out of memory. Now > I can crash the kernel any time I want with a badly written driver/module. > > Best regards, > Liviu > >> >> Sean >> >> >> > >> > BUG_ON() can be useful for those weird bugs where somewhere deep >> > down you hit a null pointer and you can't figure out where the >> > bad pointer came from. So you might sprinkle a few BUG_ONs() >> > further up to catch it sooner. Esp. if you can't reproduce the >> > bug yourself and have to rely on user(s) to find it for you. >> > >> > Even WARN_ON() w/ or w/o an early bailout might be a decent idea >> > sometimes since it might have a slightly higher chance of keeping >> > the kernel in working condition, but IMO just blindly throwing >> > it around everywhere is not a good approach. >> > >> > -- >> > Ville Syrjälä >> > Intel OTC >> > _______________________________________________ >> > dri-devel mailing list >> > dri-devel@lists.freedesktop.org >> > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > ==================== > | I would like to | > | fix the world, | > | but they're not | > | giving me the | > \ source code! / > --------------- > ¯\_(ツ)_/¯ _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 17:35 ` Rob Clark @ 2016-11-23 10:52 ` Liviu Dudau -1 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-23 10:52 UTC (permalink / raw) To: Eric Engestrom Cc: David Airlie, DRI devel, LKML, Rob Clark, Jani Nikula, Daniel Vetter drm_get_format_name() de-references the buf parameter without checking if the pointer was not NULL. Given that the function is EXPORT-ed, lets sanitise the parameters before proceeding. v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) Cc: Eric Engestrom <eric@engestrom.ch> Cc: Rob Clark <robdclark@gmail.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> --- I still think sanity checking the parameters of an exported function is worth doing, even if the way one triggers the NULL pointer crash is priviledged. Not a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf pointer, but that is a matter of taste. drivers/gpu/drm/drm_fourcc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index 90d2cc8..6d80239 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c @@ -85,6 +85,8 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); */ const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) { + BUG_ON(!buf); + snprintf(buf->str, sizeof(buf->str), "%c%c%c%c %s-endian (0x%08x)", printable_char(format & 0xff), -- 2.10.2 ^ permalink raw reply related [flat|nested] 32+ messages in thread
* [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-23 10:52 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-23 10:52 UTC (permalink / raw) To: Eric Engestrom; +Cc: Daniel Vetter, LKML, DRI devel, Jani Nikula drm_get_format_name() de-references the buf parameter without checking if the pointer was not NULL. Given that the function is EXPORT-ed, lets sanitise the parameters before proceeding. v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) Cc: Eric Engestrom <eric@engestrom.ch> Cc: Rob Clark <robdclark@gmail.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> --- I still think sanity checking the parameters of an exported function is worth doing, even if the way one triggers the NULL pointer crash is priviledged. Not a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf pointer, but that is a matter of taste. drivers/gpu/drm/drm_fourcc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index 90d2cc8..6d80239 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c @@ -85,6 +85,8 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); */ const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) { + BUG_ON(!buf); + snprintf(buf->str, sizeof(buf->str), "%c%c%c%c %s-endian (0x%08x)", printable_char(format & 0xff), -- 2.10.2 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply related [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-23 10:52 ` Liviu Dudau @ 2016-11-23 11:00 ` Jani Nikula -1 siblings, 0 replies; 32+ messages in thread From: Jani Nikula @ 2016-11-23 11:00 UTC (permalink / raw) To: Liviu Dudau, Eric Engestrom Cc: David Airlie, DRI devel, LKML, Rob Clark, Daniel Vetter On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > drm_get_format_name() de-references the buf parameter without checking > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > sanitise the parameters before proceeding. > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > Cc: Eric Engestrom <eric@engestrom.ch> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Jani Nikula <jani.nikula@intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > --- > I still think sanity checking the parameters of an exported function is worth > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > pointer, but that is a matter of taste. There really is no meaningful difference between doing BUG_ON(!bug) vs. just letting buf->str oops. The kernel is full of functions that expect sensible pointers, and I don't see why this one in particular should be so special to warrant a BUG_ON(). BR, Jani. > > > drivers/gpu/drm/drm_fourcc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index 90d2cc8..6d80239 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -85,6 +85,8 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > */ > const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > { > + BUG_ON(!buf); > + > snprintf(buf->str, sizeof(buf->str), > "%c%c%c%c %s-endian (0x%08x)", > printable_char(format & 0xff), -- Jani Nikula, Intel Open Source Technology Center ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-23 11:00 ` Jani Nikula 0 siblings, 0 replies; 32+ messages in thread From: Jani Nikula @ 2016-11-23 11:00 UTC (permalink / raw) To: Liviu Dudau, Eric Engestrom; +Cc: Daniel Vetter, LKML, DRI devel On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > drm_get_format_name() de-references the buf parameter without checking > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > sanitise the parameters before proceeding. > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > Cc: Eric Engestrom <eric@engestrom.ch> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Jani Nikula <jani.nikula@intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > --- > I still think sanity checking the parameters of an exported function is worth > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > pointer, but that is a matter of taste. There really is no meaningful difference between doing BUG_ON(!bug) vs. just letting buf->str oops. The kernel is full of functions that expect sensible pointers, and I don't see why this one in particular should be so special to warrant a BUG_ON(). BR, Jani. > > > drivers/gpu/drm/drm_fourcc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > index 90d2cc8..6d80239 100644 > --- a/drivers/gpu/drm/drm_fourcc.c > +++ b/drivers/gpu/drm/drm_fourcc.c > @@ -85,6 +85,8 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > */ > const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > { > + BUG_ON(!buf); > + > snprintf(buf->str, sizeof(buf->str), > "%c%c%c%c %s-endian (0x%08x)", > printable_char(format & 0xff), -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-23 11:00 ` Jani Nikula @ 2016-11-23 11:23 ` Liviu Dudau -1 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-23 11:23 UTC (permalink / raw) To: Jani Nikula; +Cc: Eric Engestrom, Daniel Vetter, LKML, DRI devel On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > > drm_get_format_name() de-references the buf parameter without checking > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > > sanitise the parameters before proceeding. > > > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > > > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > > Cc: Eric Engestrom <eric@engestrom.ch> > > Cc: Rob Clark <robdclark@gmail.com> > > Cc: Jani Nikula <jani.nikula@intel.com> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > > --- > > I still think sanity checking the parameters of an exported function is worth > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > > pointer, but that is a matter of taste. > > There really is no meaningful difference between doing BUG_ON(!bug) > vs. just letting buf->str oops. The kernel is full of functions that > expect sensible pointers, and I don't see why this one in particular > should be so special to warrant a BUG_ON(). Agree. That is why I prefer v1 where I return immediately on NULL pointers. Best regards, Liviu > > BR, > Jani. > > > > > > > drivers/gpu/drm/drm_fourcc.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > > index 90d2cc8..6d80239 100644 > > --- a/drivers/gpu/drm/drm_fourcc.c > > +++ b/drivers/gpu/drm/drm_fourcc.c > > @@ -85,6 +85,8 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > > */ > > const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > > { > > + BUG_ON(!buf); > > + > > snprintf(buf->str, sizeof(buf->str), > > "%c%c%c%c %s-endian (0x%08x)", > > printable_char(format & 0xff), > > -- > Jani Nikula, Intel Open Source Technology Center > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-23 11:23 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-23 11:23 UTC (permalink / raw) To: Jani Nikula; +Cc: Daniel Vetter, Eric Engestrom, LKML, DRI devel On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > > drm_get_format_name() de-references the buf parameter without checking > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > > sanitise the parameters before proceeding. > > > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > > > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > > Cc: Eric Engestrom <eric@engestrom.ch> > > Cc: Rob Clark <robdclark@gmail.com> > > Cc: Jani Nikula <jani.nikula@intel.com> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > > --- > > I still think sanity checking the parameters of an exported function is worth > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > > pointer, but that is a matter of taste. > > There really is no meaningful difference between doing BUG_ON(!bug) > vs. just letting buf->str oops. The kernel is full of functions that > expect sensible pointers, and I don't see why this one in particular > should be so special to warrant a BUG_ON(). Agree. That is why I prefer v1 where I return immediately on NULL pointers. Best regards, Liviu > > BR, > Jani. > > > > > > > drivers/gpu/drm/drm_fourcc.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > > index 90d2cc8..6d80239 100644 > > --- a/drivers/gpu/drm/drm_fourcc.c > > +++ b/drivers/gpu/drm/drm_fourcc.c > > @@ -85,6 +85,8 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > > */ > > const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > > { > > + BUG_ON(!buf); > > + > > snprintf(buf->str, sizeof(buf->str), > > "%c%c%c%c %s-endian (0x%08x)", > > printable_char(format & 0xff), > > -- > Jani Nikula, Intel Open Source Technology Center > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-23 11:23 ` Liviu Dudau @ 2016-11-23 12:26 ` Daniel Vetter -1 siblings, 0 replies; 32+ messages in thread From: Daniel Vetter @ 2016-11-23 12:26 UTC (permalink / raw) To: Liviu Dudau; +Cc: Jani Nikula, Eric Engestrom, Daniel Vetter, LKML, DRI devel On Wed, Nov 23, 2016 at 11:23:23AM +0000, Liviu Dudau wrote: > On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: > > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > > > drm_get_format_name() de-references the buf parameter without checking > > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > > > sanitise the parameters before proceeding. > > > > > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > > > > > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > > > Cc: Eric Engestrom <eric@engestrom.ch> > > > Cc: Rob Clark <robdclark@gmail.com> > > > Cc: Jani Nikula <jani.nikula@intel.com> > > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > > > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > > > --- > > > I still think sanity checking the parameters of an exported function is worth > > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > > > pointer, but that is a matter of taste. > > > > There really is no meaningful difference between doing BUG_ON(!bug) > > vs. just letting buf->str oops. The kernel is full of functions that > > expect sensible pointers, and I don't see why this one in particular > > should be so special to warrant a BUG_ON(). > > Agree. That is why I prefer v1 where I return immediately on NULL pointers. The question for v1 is why did you hit that? "broken driver code" isn't really a good reason, au contraire it's a reason to not merge your patch: We do not want to hide driver bugs silently. There's definitely cases where handling NULL automatically is reasonable, e.g. kfree(). But a NULL drm_format_name_buf sounds like, at least a quick grep shows that all callers just put this struct onto the stack. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-23 12:26 ` Daniel Vetter 0 siblings, 0 replies; 32+ messages in thread From: Daniel Vetter @ 2016-11-23 12:26 UTC (permalink / raw) To: Liviu Dudau; +Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Wed, Nov 23, 2016 at 11:23:23AM +0000, Liviu Dudau wrote: > On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: > > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > > > drm_get_format_name() de-references the buf parameter without checking > > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > > > sanitise the parameters before proceeding. > > > > > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > > > > > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > > > Cc: Eric Engestrom <eric@engestrom.ch> > > > Cc: Rob Clark <robdclark@gmail.com> > > > Cc: Jani Nikula <jani.nikula@intel.com> > > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > > > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > > > --- > > > I still think sanity checking the parameters of an exported function is worth > > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > > > pointer, but that is a matter of taste. > > > > There really is no meaningful difference between doing BUG_ON(!bug) > > vs. just letting buf->str oops. The kernel is full of functions that > > expect sensible pointers, and I don't see why this one in particular > > should be so special to warrant a BUG_ON(). > > Agree. That is why I prefer v1 where I return immediately on NULL pointers. The question for v1 is why did you hit that? "broken driver code" isn't really a good reason, au contraire it's a reason to not merge your patch: We do not want to hide driver bugs silently. There's definitely cases where handling NULL automatically is reasonable, e.g. kfree(). But a NULL drm_format_name_buf sounds like, at least a quick grep shows that all callers just put this struct onto the stack. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-23 12:26 ` Daniel Vetter @ 2016-11-23 12:47 ` Jani Nikula -1 siblings, 0 replies; 32+ messages in thread From: Jani Nikula @ 2016-11-23 12:47 UTC (permalink / raw) To: Daniel Vetter, Liviu Dudau; +Cc: Daniel Vetter, Eric Engestrom, LKML, DRI devel On Wed, 23 Nov 2016, Daniel Vetter <daniel@ffwll.ch> wrote: > On Wed, Nov 23, 2016 at 11:23:23AM +0000, Liviu Dudau wrote: >> On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: >> > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: >> > > drm_get_format_name() de-references the buf parameter without checking >> > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> > > sanitise the parameters before proceeding. >> > > >> > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. >> > > >> > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> > > Cc: Eric Engestrom <eric@engestrom.ch> >> > > Cc: Rob Clark <robdclark@gmail.com> >> > > Cc: Jani Nikula <jani.nikula@intel.com> >> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> > > >> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> > > --- >> > > I still think sanity checking the parameters of an exported function is worth >> > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not >> > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf >> > > pointer, but that is a matter of taste. >> > >> > There really is no meaningful difference between doing BUG_ON(!bug) >> > vs. just letting buf->str oops. The kernel is full of functions that >> > expect sensible pointers, and I don't see why this one in particular >> > should be so special to warrant a BUG_ON(). >> >> Agree. That is why I prefer v1 where I return immediately on NULL pointers. > > The question for v1 is why did you hit that? "broken driver code" isn't > really a good reason, au contraire it's a reason to not merge your patch: > We do not want to hide driver bugs silently. Moreover, v1 puts the burden back on the *caller* of the function to check for NULL return, while it previously could not even return NULL. The function is fine. It isn't broken. Don't try to fix it. BR, Jani. > > There's definitely cases where handling NULL automatically is reasonable, > e.g. kfree(). But a NULL drm_format_name_buf sounds like, at least a quick > grep shows that all callers just put this struct onto the stack. > -Daniel -- Jani Nikula, Intel Open Source Technology Center ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-23 12:47 ` Jani Nikula 0 siblings, 0 replies; 32+ messages in thread From: Jani Nikula @ 2016-11-23 12:47 UTC (permalink / raw) To: Daniel Vetter, Liviu Dudau; +Cc: Daniel Vetter, Eric Engestrom, LKML, DRI devel On Wed, 23 Nov 2016, Daniel Vetter <daniel@ffwll.ch> wrote: > On Wed, Nov 23, 2016 at 11:23:23AM +0000, Liviu Dudau wrote: >> On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: >> > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: >> > > drm_get_format_name() de-references the buf parameter without checking >> > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets >> > > sanitise the parameters before proceeding. >> > > >> > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. >> > > >> > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) >> > > Cc: Eric Engestrom <eric@engestrom.ch> >> > > Cc: Rob Clark <robdclark@gmail.com> >> > > Cc: Jani Nikula <jani.nikula@intel.com> >> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> > > >> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> >> > > --- >> > > I still think sanity checking the parameters of an exported function is worth >> > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not >> > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf >> > > pointer, but that is a matter of taste. >> > >> > There really is no meaningful difference between doing BUG_ON(!bug) >> > vs. just letting buf->str oops. The kernel is full of functions that >> > expect sensible pointers, and I don't see why this one in particular >> > should be so special to warrant a BUG_ON(). >> >> Agree. That is why I prefer v1 where I return immediately on NULL pointers. > > The question for v1 is why did you hit that? "broken driver code" isn't > really a good reason, au contraire it's a reason to not merge your patch: > We do not want to hide driver bugs silently. Moreover, v1 puts the burden back on the *caller* of the function to check for NULL return, while it previously could not even return NULL. The function is fine. It isn't broken. Don't try to fix it. BR, Jani. > > There's definitely cases where handling NULL automatically is reasonable, > e.g. kfree(). But a NULL drm_format_name_buf sounds like, at least a quick > grep shows that all callers just put this struct onto the stack. > -Daniel -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-23 12:47 ` Jani Nikula @ 2016-11-23 13:38 ` Liviu Dudau -1 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-23 13:38 UTC (permalink / raw) To: Jani Nikula; +Cc: Daniel Vetter, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Wed, Nov 23, 2016 at 02:47:53PM +0200, Jani Nikula wrote: > On Wed, 23 Nov 2016, Daniel Vetter <daniel@ffwll.ch> wrote: > > On Wed, Nov 23, 2016 at 11:23:23AM +0000, Liviu Dudau wrote: > >> On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: > >> > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > >> > > drm_get_format_name() de-references the buf parameter without checking > >> > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> > > sanitise the parameters before proceeding. > >> > > > >> > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > >> > > > >> > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> > > Cc: Eric Engestrom <eric@engestrom.ch> > >> > > Cc: Rob Clark <robdclark@gmail.com> > >> > > Cc: Jani Nikula <jani.nikula@intel.com> > >> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> > > > >> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> > > --- > >> > > I still think sanity checking the parameters of an exported function is worth > >> > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > >> > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > >> > > pointer, but that is a matter of taste. > >> > > >> > There really is no meaningful difference between doing BUG_ON(!bug) > >> > vs. just letting buf->str oops. The kernel is full of functions that > >> > expect sensible pointers, and I don't see why this one in particular > >> > should be so special to warrant a BUG_ON(). > >> > >> Agree. That is why I prefer v1 where I return immediately on NULL pointers. > > > > The question for v1 is why did you hit that? "broken driver code" isn't > > really a good reason, au contraire it's a reason to not merge your patch: > > We do not want to hide driver bugs silently. I was updating a stashed series and discovered that signature of the function has changed. When I looked at how it changed and I got past the "you pass as a parameter a pointer to a struct that is used as a buffer and then that buffer is returned by function" weirdness, I thought that at least checking for bad parameters should be done. > > Moreover, v1 puts the burden back on the *caller* of the function to > check for NULL return, while it previously could not even return NULL. > > The function is fine. It isn't broken. Don't try to fix it. OK. I just like defensive programming, that's all. :) Best regards, Liviu > > BR, > Jani. > > > > > > > There's definitely cases where handling NULL automatically is reasonable, > > e.g. kfree(). But a NULL drm_format_name_buf sounds like, at least a quick > > grep shows that all callers just put this struct onto the stack. > > -Daniel > > -- > Jani Nikula, Intel Open Source Technology Center -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH v2] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-23 13:38 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-23 13:38 UTC (permalink / raw) To: Jani Nikula; +Cc: Daniel Vetter, DRI devel, Eric Engestrom, LKML On Wed, Nov 23, 2016 at 02:47:53PM +0200, Jani Nikula wrote: > On Wed, 23 Nov 2016, Daniel Vetter <daniel@ffwll.ch> wrote: > > On Wed, Nov 23, 2016 at 11:23:23AM +0000, Liviu Dudau wrote: > >> On Wed, Nov 23, 2016 at 01:00:07PM +0200, Jani Nikula wrote: > >> > On Wed, 23 Nov 2016, Liviu Dudau <Liviu.Dudau@arm.com> wrote: > >> > > drm_get_format_name() de-references the buf parameter without checking > >> > > if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> > > sanitise the parameters before proceeding. > >> > > > >> > > v2: Use BUG_ON() to annoy users that did not pass valid parameters to function. > >> > > > >> > > Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> > > Cc: Eric Engestrom <eric@engestrom.ch> > >> > > Cc: Rob Clark <robdclark@gmail.com> > >> > > Cc: Jani Nikula <jani.nikula@intel.com> > >> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> > > > >> > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> > > --- > >> > > I still think sanity checking the parameters of an exported function is worth > >> > > doing, even if the way one triggers the NULL pointer crash is priviledged. Not > >> > > a big fan of the verbosity of BUG_ON() and would rather silently reject NULL buf > >> > > pointer, but that is a matter of taste. > >> > > >> > There really is no meaningful difference between doing BUG_ON(!bug) > >> > vs. just letting buf->str oops. The kernel is full of functions that > >> > expect sensible pointers, and I don't see why this one in particular > >> > should be so special to warrant a BUG_ON(). > >> > >> Agree. That is why I prefer v1 where I return immediately on NULL pointers. > > > > The question for v1 is why did you hit that? "broken driver code" isn't > > really a good reason, au contraire it's a reason to not merge your patch: > > We do not want to hide driver bugs silently. I was updating a stashed series and discovered that signature of the function has changed. When I looked at how it changed and I got past the "you pass as a parameter a pointer to a struct that is used as a buffer and then that buffer is returned by function" weirdness, I thought that at least checking for bad parameters should be done. > > Moreover, v1 puts the burden back on the *caller* of the function to > check for NULL return, while it previously could not even return NULL. > > The function is fine. It isn't broken. Don't try to fix it. OK. I just like defensive programming, that's all. :) Best regards, Liviu > > BR, > Jani. > > > > > > > There's definitely cases where handling NULL automatically is reasonable, > > e.g. kfree(). But a NULL drm_format_name_buf sounds like, at least a quick > > grep shows that all callers just put this struct onto the stack. > > -Daniel > > -- > Jani Nikula, Intel Open Source Technology Center -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. 2016-11-22 17:23 ` Rob Clark @ 2016-11-22 18:49 ` Liviu Dudau -1 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-22 18:49 UTC (permalink / raw) To: Rob Clark Cc: Ville Syrjälä, Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> drm_get_format_name() de-references the buf parameter without checking > >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> sanitise the parameters before proceeding. > >> > >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> Cc: Eric Engestrom <eric@engestrom.ch> > >> Cc: Rob Clark <robdclark@gmail.com> > >> Cc: Jani Nikula <jani.nikula@intel.com> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> > >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> --- > >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> index 90d2cc8..0a3ff0b 100644 > >> --- a/drivers/gpu/drm/drm_fourcc.c > >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> */ > >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> { > >> + if (!buf) > >> + return NULL; > >> + > > > > Seems rather pointless to me. Why would you ever pass NULL to this guy? > > perhaps BUG_ON(!buf)... Nah, I don't want to start spamming the logs. You passed nothing, you get nothing, no reason to throw a tantrum. Best regards, Liviu > > BR, > -R > > >> snprintf(buf->str, sizeof(buf->str), > >> "%c%c%c%c %s-endian (0x%08x)", > >> printable_char(format & 0xff), > >> -- > >> 2.10.2 > >> > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@lists.freedesktop.org > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > > Ville Syrjälä > > Intel OTC > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ ^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function. @ 2016-11-22 18:49 ` Liviu Dudau 0 siblings, 0 replies; 32+ messages in thread From: Liviu Dudau @ 2016-11-22 18:49 UTC (permalink / raw) To: Rob Clark; +Cc: Jani Nikula, Daniel Vetter, Eric Engestrom, LKML, DRI devel On Tue, Nov 22, 2016 at 12:23:59PM -0500, Rob Clark wrote: > On Tue, Nov 22, 2016 at 11:50 AM, Ville Syrjälä > <ville.syrjala@linux.intel.com> wrote: > > On Tue, Nov 22, 2016 at 04:41:06PM +0000, Liviu Dudau wrote: > >> drm_get_format_name() de-references the buf parameter without checking > >> if the pointer was not NULL. Given that the function is EXPORT-ed, lets > >> sanitise the parameters before proceeding. > >> > >> Fixes: b3c11ac267d461d3d5 ("drm: move allocation out of drm_get_format_name()) > >> Cc: Eric Engestrom <eric@engestrom.ch> > >> Cc: Rob Clark <robdclark@gmail.com> > >> Cc: Jani Nikula <jani.nikula@intel.com> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> > >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > >> --- > >> drivers/gpu/drm/drm_fourcc.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> index 90d2cc8..0a3ff0b 100644 > >> --- a/drivers/gpu/drm/drm_fourcc.c > >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> @@ -85,6 +85,9 @@ EXPORT_SYMBOL(drm_mode_legacy_fb_format); > >> */ > >> const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf) > >> { > >> + if (!buf) > >> + return NULL; > >> + > > > > Seems rather pointless to me. Why would you ever pass NULL to this guy? > > perhaps BUG_ON(!buf)... Nah, I don't want to start spamming the logs. You passed nothing, you get nothing, no reason to throw a tantrum. Best regards, Liviu > > BR, > -R > > >> snprintf(buf->str, sizeof(buf->str), > >> "%c%c%c%c %s-endian (0x%08x)", > >> printable_char(format & 0xff), > >> -- > >> 2.10.2 > >> > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@lists.freedesktop.org > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > > Ville Syrjälä > > Intel OTC > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 32+ messages in thread
end of thread, other threads:[~2016-11-23 13:38 UTC | newest] Thread overview: 32+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-11-22 16:41 [PATCH] drm: check for NULL parameter in exported drm_get_format_name() function Liviu Dudau 2016-11-22 16:41 ` Liviu Dudau 2016-11-22 16:50 ` Ville Syrjälä 2016-11-22 16:50 ` Ville Syrjälä 2016-11-22 17:23 ` Rob Clark 2016-11-22 17:23 ` Rob Clark 2016-11-22 17:31 ` Ville Syrjälä 2016-11-22 17:31 ` Ville Syrjälä 2016-11-22 17:35 ` Rob Clark 2016-11-22 17:35 ` Rob Clark 2016-11-22 18:06 ` Ville Syrjälä 2016-11-22 18:06 ` Ville Syrjälä 2016-11-22 18:15 ` Sean Paul 2016-11-22 18:15 ` Sean Paul 2016-11-22 18:47 ` Liviu Dudau 2016-11-22 18:47 ` Liviu Dudau 2016-11-22 21:46 ` Rob Clark 2016-11-22 21:46 ` Rob Clark 2016-11-23 10:52 ` [PATCH v2] " Liviu Dudau 2016-11-23 10:52 ` Liviu Dudau 2016-11-23 11:00 ` Jani Nikula 2016-11-23 11:00 ` Jani Nikula 2016-11-23 11:23 ` Liviu Dudau 2016-11-23 11:23 ` Liviu Dudau 2016-11-23 12:26 ` Daniel Vetter 2016-11-23 12:26 ` Daniel Vetter 2016-11-23 12:47 ` Jani Nikula 2016-11-23 12:47 ` Jani Nikula 2016-11-23 13:38 ` Liviu Dudau 2016-11-23 13:38 ` Liviu Dudau 2016-11-22 18:49 ` [PATCH] " Liviu Dudau 2016-11-22 18:49 ` Liviu Dudau
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