* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-01-05 17:35 [PATCH] drm/dp: Remove common Post Cursor2 register handling Kees Cook
@ 2022-01-05 18:00 ` Jani Nikula
2022-01-05 22:11 ` Kees Cook
2022-01-18 19:11 ` Gustavo A. R. Silva
2022-02-05 1:41 ` Kees Cook
2 siblings, 1 reply; 8+ messages in thread
From: Jani Nikula @ 2022-01-05 18:00 UTC (permalink / raw)
To: Kees Cook, Maarten Lankhorst
Cc: Kees Cook, Maxime Ripard, Thomas Zimmermann, David Airlie,
Daniel Vetter, dri-devel, Thierry Reding, Jonathan Hunter,
Philipp Zabel, Lyude Paul, linux-kernel, linux-tegra,
linux-hardening
On Wed, 05 Jan 2022, Kees Cook <keescook@chromium.org> wrote:
> The link_status array was not large enough to read the Adjust Request
> Post Cursor2 register, so remove the common helper function to avoid
> an OOB read, found with a -Warray-bounds build:
>
> drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
> drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
> 59 | return link_status[r - DP_LANE0_1_STATUS];
> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
> 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Replace the only user of the helper with an open-coded fetch and decode,
> similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
>
> Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> This is the alternative to:
> https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
> ---
> drivers/gpu/drm/drm_dp_helper.c | 10 ----------
> drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
> include/drm/drm_dp_helper.h | 2 --
> 3 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 23f9073bc473..c9528aa62c9c 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> }
> EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
>
> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> - unsigned int lane)
> -{
> - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
> - u8 value = dp_link_status(link_status, offset);
> -
> - return (value >> (lane << 1)) & 0x3;
> -}
> -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
> -
> static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
> {
> if (rd_interval > 4)
> diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
> index 70dfb7d1dec5..f5535eb04c6b 100644
> --- a/drivers/gpu/drm/tegra/dp.c
> +++ b/drivers/gpu/drm/tegra/dp.c
> @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> {
> struct drm_dp_link_train_set *adjust = &link->train.adjust;
> unsigned int i;
> + u8 post_cursor;
> + int err;
> +
> + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
> + &post_cursor, sizeof(post_cursor));
There's a drm_dp_dpcd_readb() for the common 1-byte reads. Other than
that,
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Though obviously that's not enough to actually merge to tegra.
> + if (err < 0) {
> + DRM_ERROR("failed to read post_cursor2: %d\n", err);
> + post_cursor = 0;
> + }
>
> for (i = 0; i < link->lanes; i++) {
> adjust->voltage_swing[i] =
> @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> DP_TRAIN_PRE_EMPHASIS_SHIFT;
>
> adjust->post_cursor[i] =
> - drm_dp_get_adjust_request_post_cursor(status, i);
> + (post_cursor >> (i << 1)) & 0x3;
> }
> }
>
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 472dac376284..fdf3cf6ccc02 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
> int lane);
> u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> int lane);
> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> - unsigned int lane);
>
> #define DP_BRANCH_OUI_HEADER_SIZE 0xc
> #define DP_RECEIVER_CAP_SIZE 0xf
--
Jani Nikula, Intel Open Source Graphics Center
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-01-05 18:00 ` Jani Nikula
@ 2022-01-05 22:11 ` Kees Cook
2022-01-07 10:58 ` Jani Nikula
0 siblings, 1 reply; 8+ messages in thread
From: Kees Cook @ 2022-01-05 22:11 UTC (permalink / raw)
To: Jani Nikula
Cc: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Daniel Vetter, dri-devel, Thierry Reding,
Jonathan Hunter, Philipp Zabel, Lyude Paul, linux-kernel,
linux-tegra, linux-hardening
On Wed, Jan 05, 2022 at 08:00:50PM +0200, Jani Nikula wrote:
> On Wed, 05 Jan 2022, Kees Cook <keescook@chromium.org> wrote:
> > The link_status array was not large enough to read the Adjust Request
> > Post Cursor2 register, so remove the common helper function to avoid
> > an OOB read, found with a -Warray-bounds build:
> >
> > drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
> > drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
> > 59 | return link_status[r - DP_LANE0_1_STATUS];
> > | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
> > drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
> > 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> > | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Replace the only user of the helper with an open-coded fetch and decode,
> > similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
> >
> > Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Maxime Ripard <mripard@kernel.org>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: David Airlie <airlied@linux.ie>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Cc: dri-devel@lists.freedesktop.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> > This is the alternative to:
> > https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
> > ---
> > drivers/gpu/drm/drm_dp_helper.c | 10 ----------
> > drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
> > include/drm/drm_dp_helper.h | 2 --
> > 3 files changed, 10 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> > index 23f9073bc473..c9528aa62c9c 100644
> > --- a/drivers/gpu/drm/drm_dp_helper.c
> > +++ b/drivers/gpu/drm/drm_dp_helper.c
> > @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> > }
> > EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
> >
> > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> > - unsigned int lane)
> > -{
> > - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
> > - u8 value = dp_link_status(link_status, offset);
> > -
> > - return (value >> (lane << 1)) & 0x3;
> > -}
> > -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
> > -
> > static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
> > {
> > if (rd_interval > 4)
> > diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
> > index 70dfb7d1dec5..f5535eb04c6b 100644
> > --- a/drivers/gpu/drm/tegra/dp.c
> > +++ b/drivers/gpu/drm/tegra/dp.c
> > @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> > {
> > struct drm_dp_link_train_set *adjust = &link->train.adjust;
> > unsigned int i;
> > + u8 post_cursor;
> > + int err;
> > +
> > + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
> > + &post_cursor, sizeof(post_cursor));
>
> There's a drm_dp_dpcd_readb() for the common 1-byte reads. Other than
> that,
>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Thanks!
>
> Though obviously that's not enough to actually merge to tegra.
As in, "a review by Jani isn't sufficient to land via the tegra tree"?
What should next steps be?
-Kees
>
> > + if (err < 0) {
> > + DRM_ERROR("failed to read post_cursor2: %d\n", err);
> > + post_cursor = 0;
> > + }
> >
> > for (i = 0; i < link->lanes; i++) {
> > adjust->voltage_swing[i] =
> > @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> > DP_TRAIN_PRE_EMPHASIS_SHIFT;
> >
> > adjust->post_cursor[i] =
> > - drm_dp_get_adjust_request_post_cursor(status, i);
> > + (post_cursor >> (i << 1)) & 0x3;
> > }
> > }
> >
> > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> > index 472dac376284..fdf3cf6ccc02 100644
> > --- a/include/drm/drm_dp_helper.h
> > +++ b/include/drm/drm_dp_helper.h
> > @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
> > int lane);
> > u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> > int lane);
> > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> > - unsigned int lane);
> >
> > #define DP_BRANCH_OUI_HEADER_SIZE 0xc
> > #define DP_RECEIVER_CAP_SIZE 0xf
>
> --
> Jani Nikula, Intel Open Source Graphics Center
--
Kees Cook
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-01-05 22:11 ` Kees Cook
@ 2022-01-07 10:58 ` Jani Nikula
0 siblings, 0 replies; 8+ messages in thread
From: Jani Nikula @ 2022-01-07 10:58 UTC (permalink / raw)
To: Kees Cook
Cc: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Daniel Vetter, dri-devel, Thierry Reding,
Jonathan Hunter, Philipp Zabel, Lyude Paul, linux-kernel,
linux-tegra, linux-hardening
On Wed, 05 Jan 2022, Kees Cook <keescook@chromium.org> wrote:
> On Wed, Jan 05, 2022 at 08:00:50PM +0200, Jani Nikula wrote:
>> On Wed, 05 Jan 2022, Kees Cook <keescook@chromium.org> wrote:
>> > The link_status array was not large enough to read the Adjust Request
>> > Post Cursor2 register, so remove the common helper function to avoid
>> > an OOB read, found with a -Warray-bounds build:
>> >
>> > drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
>> > drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
>> > 59 | return link_status[r - DP_LANE0_1_STATUS];
>> > | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
>> > drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
>> > 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
>> > | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >
>> > Replace the only user of the helper with an open-coded fetch and decode,
>> > similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
>> >
>> > Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
>> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> > Cc: Maxime Ripard <mripard@kernel.org>
>> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> > Cc: David Airlie <airlied@linux.ie>
>> > Cc: Daniel Vetter <daniel@ffwll.ch>
>> > Cc: dri-devel@lists.freedesktop.org
>> > Signed-off-by: Kees Cook <keescook@chromium.org>
>> > ---
>> > This is the alternative to:
>> > https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
>> > ---
>> > drivers/gpu/drm/drm_dp_helper.c | 10 ----------
>> > drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
>> > include/drm/drm_dp_helper.h | 2 --
>> > 3 files changed, 10 insertions(+), 13 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
>> > index 23f9073bc473..c9528aa62c9c 100644
>> > --- a/drivers/gpu/drm/drm_dp_helper.c
>> > +++ b/drivers/gpu/drm/drm_dp_helper.c
>> > @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
>> > }
>> > EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
>> >
>> > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
>> > - unsigned int lane)
>> > -{
>> > - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
>> > - u8 value = dp_link_status(link_status, offset);
>> > -
>> > - return (value >> (lane << 1)) & 0x3;
>> > -}
>> > -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
>> > -
>> > static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
>> > {
>> > if (rd_interval > 4)
>> > diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
>> > index 70dfb7d1dec5..f5535eb04c6b 100644
>> > --- a/drivers/gpu/drm/tegra/dp.c
>> > +++ b/drivers/gpu/drm/tegra/dp.c
>> > @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
>> > {
>> > struct drm_dp_link_train_set *adjust = &link->train.adjust;
>> > unsigned int i;
>> > + u8 post_cursor;
>> > + int err;
>> > +
>> > + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
>> > + &post_cursor, sizeof(post_cursor));
>>
>> There's a drm_dp_dpcd_readb() for the common 1-byte reads. Other than
>> that,
>>
>> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
>
> Thanks!
>
>>
>> Though obviously that's not enough to actually merge to tegra.
>
> As in, "a review by Jani isn't sufficient to land via the tegra tree"?
Yeah. Or, in this case, via any tree, really.
> What should next steps be?
Get an ack from tegra and/or drm-misc maintainers. All the relevant
folks and lists are in the recipients already.
BR,
Jani.
>
> -Kees
>
>>
>> > + if (err < 0) {
>> > + DRM_ERROR("failed to read post_cursor2: %d\n", err);
>> > + post_cursor = 0;
>> > + }
>> >
>> > for (i = 0; i < link->lanes; i++) {
>> > adjust->voltage_swing[i] =
>> > @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
>> > DP_TRAIN_PRE_EMPHASIS_SHIFT;
>> >
>> > adjust->post_cursor[i] =
>> > - drm_dp_get_adjust_request_post_cursor(status, i);
>> > + (post_cursor >> (i << 1)) & 0x3;
>> > }
>> > }
>> >
>> > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
>> > index 472dac376284..fdf3cf6ccc02 100644
>> > --- a/include/drm/drm_dp_helper.h
>> > +++ b/include/drm/drm_dp_helper.h
>> > @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
>> > int lane);
>> > u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
>> > int lane);
>> > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
>> > - unsigned int lane);
>> >
>> > #define DP_BRANCH_OUI_HEADER_SIZE 0xc
>> > #define DP_RECEIVER_CAP_SIZE 0xf
>>
>> --
>> Jani Nikula, Intel Open Source Graphics Center
--
Jani Nikula, Intel Open Source Graphics Center
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-01-05 17:35 [PATCH] drm/dp: Remove common Post Cursor2 register handling Kees Cook
2022-01-05 18:00 ` Jani Nikula
@ 2022-01-18 19:11 ` Gustavo A. R. Silva
2022-01-18 21:37 ` Kees Cook
2022-02-05 1:41 ` Kees Cook
2 siblings, 1 reply; 8+ messages in thread
From: Gustavo A. R. Silva @ 2022-01-18 19:11 UTC (permalink / raw)
To: Kees Cook, Maarten Lankhorst
Cc: Maxime Ripard, Thomas Zimmermann, David Airlie, Daniel Vetter,
dri-devel, Jani Nikula, Thierry Reding, Jonathan Hunter,
Philipp Zabel, Lyude Paul, linux-kernel, linux-tegra,
linux-hardening
On 1/5/22 11:35, Kees Cook wrote:
> The link_status array was not large enough to read the Adjust Request
> Post Cursor2 register, so remove the common helper function to avoid
> an OOB read, found with a -Warray-bounds build:
>
> drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
> drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
> 59 | return link_status[r - DP_LANE0_1_STATUS];
> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
> 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Replace the only user of the helper with an open-coded fetch and decode,
> similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
>
> Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
This should be tagged for -stable:
Cc: stable@vger.kernel.org
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Thanks
--
Gustavo
> ---
> This is the alternative to:
> https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
> ---
> drivers/gpu/drm/drm_dp_helper.c | 10 ----------
> drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
> include/drm/drm_dp_helper.h | 2 --
> 3 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 23f9073bc473..c9528aa62c9c 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> }
> EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
>
> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> - unsigned int lane)
> -{
> - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
> - u8 value = dp_link_status(link_status, offset);
> -
> - return (value >> (lane << 1)) & 0x3;
> -}
> -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
> -
> static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
> {
> if (rd_interval > 4)
> diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
> index 70dfb7d1dec5..f5535eb04c6b 100644
> --- a/drivers/gpu/drm/tegra/dp.c
> +++ b/drivers/gpu/drm/tegra/dp.c
> @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> {
> struct drm_dp_link_train_set *adjust = &link->train.adjust;
> unsigned int i;
> + u8 post_cursor;
> + int err;
> +
> + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
> + &post_cursor, sizeof(post_cursor));
> + if (err < 0) {
> + DRM_ERROR("failed to read post_cursor2: %d\n", err);
> + post_cursor = 0;
> + }
>
> for (i = 0; i < link->lanes; i++) {
> adjust->voltage_swing[i] =
> @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> DP_TRAIN_PRE_EMPHASIS_SHIFT;
>
> adjust->post_cursor[i] =
> - drm_dp_get_adjust_request_post_cursor(status, i);
> + (post_cursor >> (i << 1)) & 0x3;
> }
> }
>
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 472dac376284..fdf3cf6ccc02 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
> int lane);
> u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> int lane);
> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> - unsigned int lane);
>
> #define DP_BRANCH_OUI_HEADER_SIZE 0xc
> #define DP_RECEIVER_CAP_SIZE 0xf
>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-01-18 19:11 ` Gustavo A. R. Silva
@ 2022-01-18 21:37 ` Kees Cook
0 siblings, 0 replies; 8+ messages in thread
From: Kees Cook @ 2022-01-18 21:37 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Daniel Vetter, dri-devel, Jani Nikula,
Thierry Reding, Jonathan Hunter, Philipp Zabel, Lyude Paul,
linux-kernel, linux-tegra, linux-hardening
On Tue, Jan 18, 2022 at 01:11:48PM -0600, Gustavo A. R. Silva wrote:
>
>
> On 1/5/22 11:35, Kees Cook wrote:
> > The link_status array was not large enough to read the Adjust Request
> > Post Cursor2 register, so remove the common helper function to avoid
> > an OOB read, found with a -Warray-bounds build:
> >
> > drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
> > drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
> > 59 | return link_status[r - DP_LANE0_1_STATUS];
> > | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
> > drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
> > 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> > | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Replace the only user of the helper with an open-coded fetch and decode,
> > similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
> >
> > Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
>
> This should be tagged for -stable:
>
> Cc: stable@vger.kernel.org
Ah yeah, good point. Added.
>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Maxime Ripard <mripard@kernel.org>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: David Airlie <airlied@linux.ie>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Cc: dri-devel@lists.freedesktop.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
>
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Thanks!
-Kees
>
> Thanks
> --
> Gustavo
>
> > ---
> > This is the alternative to:
> > https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
> > ---
> > drivers/gpu/drm/drm_dp_helper.c | 10 ----------
> > drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
> > include/drm/drm_dp_helper.h | 2 --
> > 3 files changed, 10 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> > index 23f9073bc473..c9528aa62c9c 100644
> > --- a/drivers/gpu/drm/drm_dp_helper.c
> > +++ b/drivers/gpu/drm/drm_dp_helper.c
> > @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> > }
> > EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
> >
> > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> > - unsigned int lane)
> > -{
> > - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
> > - u8 value = dp_link_status(link_status, offset);
> > -
> > - return (value >> (lane << 1)) & 0x3;
> > -}
> > -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
> > -
> > static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
> > {
> > if (rd_interval > 4)
> > diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
> > index 70dfb7d1dec5..f5535eb04c6b 100644
> > --- a/drivers/gpu/drm/tegra/dp.c
> > +++ b/drivers/gpu/drm/tegra/dp.c
> > @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> > {
> > struct drm_dp_link_train_set *adjust = &link->train.adjust;
> > unsigned int i;
> > + u8 post_cursor;
> > + int err;
> > +
> > + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
> > + &post_cursor, sizeof(post_cursor));
> > + if (err < 0) {
> > + DRM_ERROR("failed to read post_cursor2: %d\n", err);
> > + post_cursor = 0;
> > + }
> >
> > for (i = 0; i < link->lanes; i++) {
> > adjust->voltage_swing[i] =
> > @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> > DP_TRAIN_PRE_EMPHASIS_SHIFT;
> >
> > adjust->post_cursor[i] =
> > - drm_dp_get_adjust_request_post_cursor(status, i);
> > + (post_cursor >> (i << 1)) & 0x3;
> > }
> > }
> >
> > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> > index 472dac376284..fdf3cf6ccc02 100644
> > --- a/include/drm/drm_dp_helper.h
> > +++ b/include/drm/drm_dp_helper.h
> > @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
> > int lane);
> > u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> > int lane);
> > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> > - unsigned int lane);
> >
> > #define DP_BRANCH_OUI_HEADER_SIZE 0xc
> > #define DP_RECEIVER_CAP_SIZE 0xf
> >
--
Kees Cook
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-01-05 17:35 [PATCH] drm/dp: Remove common Post Cursor2 register handling Kees Cook
2022-01-05 18:00 ` Jani Nikula
2022-01-18 19:11 ` Gustavo A. R. Silva
@ 2022-02-05 1:41 ` Kees Cook
2022-02-07 11:04 ` Jani Nikula
2 siblings, 1 reply; 8+ messages in thread
From: Kees Cook @ 2022-02-05 1:41 UTC (permalink / raw)
To: Maarten Lankhorst, David Airlie, Daniel Vetter
Cc: Maxime Ripard, Thomas Zimmermann, dri-devel, Jani Nikula,
Thierry Reding, Jonathan Hunter, Philipp Zabel, Lyude Paul,
linux-kernel, linux-tegra, linux-hardening
Ping,
This is a OOB read fix. Can someone please pick this up?
-Kees
On Wed, Jan 05, 2022 at 09:35:07AM -0800, Kees Cook wrote:
> The link_status array was not large enough to read the Adjust Request
> Post Cursor2 register, so remove the common helper function to avoid
> an OOB read, found with a -Warray-bounds build:
>
> drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
> drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
> 59 | return link_status[r - DP_LANE0_1_STATUS];
> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
> 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Replace the only user of the helper with an open-coded fetch and decode,
> similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
>
> Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> This is the alternative to:
> https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
> ---
> drivers/gpu/drm/drm_dp_helper.c | 10 ----------
> drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
> include/drm/drm_dp_helper.h | 2 --
> 3 files changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 23f9073bc473..c9528aa62c9c 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> }
> EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
>
> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> - unsigned int lane)
> -{
> - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
> - u8 value = dp_link_status(link_status, offset);
> -
> - return (value >> (lane << 1)) & 0x3;
> -}
> -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
> -
> static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
> {
> if (rd_interval > 4)
> diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
> index 70dfb7d1dec5..f5535eb04c6b 100644
> --- a/drivers/gpu/drm/tegra/dp.c
> +++ b/drivers/gpu/drm/tegra/dp.c
> @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> {
> struct drm_dp_link_train_set *adjust = &link->train.adjust;
> unsigned int i;
> + u8 post_cursor;
> + int err;
> +
> + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
> + &post_cursor, sizeof(post_cursor));
> + if (err < 0) {
> + DRM_ERROR("failed to read post_cursor2: %d\n", err);
> + post_cursor = 0;
> + }
>
> for (i = 0; i < link->lanes; i++) {
> adjust->voltage_swing[i] =
> @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
> DP_TRAIN_PRE_EMPHASIS_SHIFT;
>
> adjust->post_cursor[i] =
> - drm_dp_get_adjust_request_post_cursor(status, i);
> + (post_cursor >> (i << 1)) & 0x3;
> }
> }
>
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 472dac376284..fdf3cf6ccc02 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
> int lane);
> u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
> int lane);
> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
> - unsigned int lane);
>
> #define DP_BRANCH_OUI_HEADER_SIZE 0xc
> #define DP_RECEIVER_CAP_SIZE 0xf
> --
> 2.30.2
>
--
Kees Cook
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling
2022-02-05 1:41 ` Kees Cook
@ 2022-02-07 11:04 ` Jani Nikula
0 siblings, 0 replies; 8+ messages in thread
From: Jani Nikula @ 2022-02-07 11:04 UTC (permalink / raw)
To: Kees Cook, Maarten Lankhorst, David Airlie, Daniel Vetter
Cc: Maxime Ripard, Thomas Zimmermann, dri-devel, Thierry Reding,
Jonathan Hunter, Philipp Zabel, Lyude Paul, linux-kernel,
linux-tegra, linux-hardening
On Fri, 04 Feb 2022, Kees Cook <keescook@chromium.org> wrote:
> Ping,
>
> This is a OOB read fix. Can someone please pick this up?
Daniel? Thierry?
As I said, I reviewed this but I'm not comfortable applying patches that
change the functionality of drivers I don't maintain.
BR,
Jani.
>
> -Kees
>
> On Wed, Jan 05, 2022 at 09:35:07AM -0800, Kees Cook wrote:
>> The link_status array was not large enough to read the Adjust Request
>> Post Cursor2 register, so remove the common helper function to avoid
>> an OOB read, found with a -Warray-bounds build:
>>
>> drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
>> drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
>> 59 | return link_status[r - DP_LANE0_1_STATUS];
>> | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
>> drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
>> 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
>> | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Replace the only user of the helper with an open-coded fetch and decode,
>> similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.
>>
>> Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Cc: Maxime Ripard <mripard@kernel.org>
>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: David Airlie <airlied@linux.ie>
>> Cc: Daniel Vetter <daniel@ffwll.ch>
>> Cc: dri-devel@lists.freedesktop.org
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>> This is the alternative to:
>> https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/
>> ---
>> drivers/gpu/drm/drm_dp_helper.c | 10 ----------
>> drivers/gpu/drm/tegra/dp.c | 11 ++++++++++-
>> include/drm/drm_dp_helper.h | 2 --
>> 3 files changed, 10 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
>> index 23f9073bc473..c9528aa62c9c 100644
>> --- a/drivers/gpu/drm/drm_dp_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_helper.c
>> @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
>> }
>> EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);
>>
>> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
>> - unsigned int lane)
>> -{
>> - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2;
>> - u8 value = dp_link_status(link_status, offset);
>> -
>> - return (value >> (lane << 1)) & 0x3;
>> -}
>> -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor);
>> -
>> static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval)
>> {
>> if (rd_interval > 4)
>> diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c
>> index 70dfb7d1dec5..f5535eb04c6b 100644
>> --- a/drivers/gpu/drm/tegra/dp.c
>> +++ b/drivers/gpu/drm/tegra/dp.c
>> @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
>> {
>> struct drm_dp_link_train_set *adjust = &link->train.adjust;
>> unsigned int i;
>> + u8 post_cursor;
>> + int err;
>> +
>> + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2,
>> + &post_cursor, sizeof(post_cursor));
>> + if (err < 0) {
>> + DRM_ERROR("failed to read post_cursor2: %d\n", err);
>> + post_cursor = 0;
>> + }
>>
>> for (i = 0; i < link->lanes; i++) {
>> adjust->voltage_swing[i] =
>> @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link,
>> DP_TRAIN_PRE_EMPHASIS_SHIFT;
>>
>> adjust->post_cursor[i] =
>> - drm_dp_get_adjust_request_post_cursor(status, i);
>> + (post_cursor >> (i << 1)) & 0x3;
>> }
>> }
>>
>> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
>> index 472dac376284..fdf3cf6ccc02 100644
>> --- a/include/drm/drm_dp_helper.h
>> +++ b/include/drm/drm_dp_helper.h
>> @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
>> int lane);
>> u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
>> int lane);
>> -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
>> - unsigned int lane);
>>
>> #define DP_BRANCH_OUI_HEADER_SIZE 0xc
>> #define DP_RECEIVER_CAP_SIZE 0xf
>> --
>> 2.30.2
>>
--
Jani Nikula, Intel Open Source Graphics Center
^ permalink raw reply [flat|nested] 8+ messages in thread