From: Thomas Zimmermann <tzimmermann@suse.de> To: Zeng Jingxiang <zengjx95@gmail.com>, anitha.chrisanthus@intel.com, edmund.j.dea@intel.com, airlied@linux.ie, daniel@ffwll.ch, laurent.pinchart@ideasonboard.com, maxime@cerno.tech, ville.syrjala@linux.intel.com Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Zeng Jingxiang <linuszeng@tencent.com> Subject: Re: [PATCH] drm/kmb: fix dereference before NULL check in kmb_plane_atomic_update() Date: Fri, 29 Jul 2022 16:23:21 +0200 [thread overview] Message-ID: <a68022f4-28d0-7743-27fe-6df652082184@suse.de> (raw) In-Reply-To: <20220729030711.2117849-1-zengjx95@gmail.com> [-- Attachment #1.1: Type: text/plain, Size: 2626 bytes --] Hi Am 29.07.22 um 05:07 schrieb Zeng Jingxiang: > From: Zeng Jingxiang <linuszeng@tencent.com> > > The "plane" pointer was access before checking if it was NULL. > > The drm_atomic_get_old_plane_state() function will dereference > the pointer "plane". > 345 struct drm_plane_state *old_plane_state = > drm_atomic_get_old_plane_state(state, plane); > 346 struct drm_plane_state *new_plane_state = > drm_atomic_get_new_plane_state(state, plane); > > A NULL check for "plane" indicates that it may be NULL > 363 if (!plane || !new_plane_state || !old_plane_state) Is this an actual bug that happens? All planes should always have a state. Therefore the tests for !new_plane_state and !old_plane_state can be removed, I'd say. Best regards Thomas > > Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic disable and update") > Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state pointer") > Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com> > --- > drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/kmb/kmb_plane.c b/drivers/gpu/drm/kmb/kmb_plane.c > index 2735b8eb3537..d2bc998b65ce 100644 > --- a/drivers/gpu/drm/kmb/kmb_plane.c > +++ b/drivers/gpu/drm/kmb/kmb_plane.c > @@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct kmb_drm_private *kmb, > static void kmb_plane_atomic_update(struct drm_plane *plane, > struct drm_atomic_state *state) > { > - struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, > - plane); > - struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, > - plane); > + struct drm_plane_state *old_plane_state, *new_plane_state; > struct drm_framebuffer *fb; > struct kmb_drm_private *kmb; > unsigned int width; > @@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct drm_plane *plane, > static dma_addr_t addr[MAX_SUB_PLANES]; > struct disp_cfg *init_disp_cfg; > > - if (!plane || !new_plane_state || !old_plane_state) > + if (!plane) > + return; > + > + old_plane_state = drm_atomic_get_old_plane_state(state, plane); > + new_plane_state = drm_atomic_get_new_plane_state(state, plane); > + > + if (!new_plane_state || !old_plane_state) > return; > > fb = new_plane_state->fb; -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 840 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Zimmermann <tzimmermann@suse.de> To: Zeng Jingxiang <zengjx95@gmail.com>, anitha.chrisanthus@intel.com, edmund.j.dea@intel.com, airlied@linux.ie, daniel@ffwll.ch, laurent.pinchart@ideasonboard.com, maxime@cerno.tech, ville.syrjala@linux.intel.com Cc: Zeng Jingxiang <linuszeng@tencent.com>, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] drm/kmb: fix dereference before NULL check in kmb_plane_atomic_update() Date: Fri, 29 Jul 2022 16:23:21 +0200 [thread overview] Message-ID: <a68022f4-28d0-7743-27fe-6df652082184@suse.de> (raw) In-Reply-To: <20220729030711.2117849-1-zengjx95@gmail.com> [-- Attachment #1.1: Type: text/plain, Size: 2626 bytes --] Hi Am 29.07.22 um 05:07 schrieb Zeng Jingxiang: > From: Zeng Jingxiang <linuszeng@tencent.com> > > The "plane" pointer was access before checking if it was NULL. > > The drm_atomic_get_old_plane_state() function will dereference > the pointer "plane". > 345 struct drm_plane_state *old_plane_state = > drm_atomic_get_old_plane_state(state, plane); > 346 struct drm_plane_state *new_plane_state = > drm_atomic_get_new_plane_state(state, plane); > > A NULL check for "plane" indicates that it may be NULL > 363 if (!plane || !new_plane_state || !old_plane_state) Is this an actual bug that happens? All planes should always have a state. Therefore the tests for !new_plane_state and !old_plane_state can be removed, I'd say. Best regards Thomas > > Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic disable and update") > Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state pointer") > Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com> > --- > drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/kmb/kmb_plane.c b/drivers/gpu/drm/kmb/kmb_plane.c > index 2735b8eb3537..d2bc998b65ce 100644 > --- a/drivers/gpu/drm/kmb/kmb_plane.c > +++ b/drivers/gpu/drm/kmb/kmb_plane.c > @@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct kmb_drm_private *kmb, > static void kmb_plane_atomic_update(struct drm_plane *plane, > struct drm_atomic_state *state) > { > - struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, > - plane); > - struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, > - plane); > + struct drm_plane_state *old_plane_state, *new_plane_state; > struct drm_framebuffer *fb; > struct kmb_drm_private *kmb; > unsigned int width; > @@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct drm_plane *plane, > static dma_addr_t addr[MAX_SUB_PLANES]; > struct disp_cfg *init_disp_cfg; > > - if (!plane || !new_plane_state || !old_plane_state) > + if (!plane) > + return; > + > + old_plane_state = drm_atomic_get_old_plane_state(state, plane); > + new_plane_state = drm_atomic_get_new_plane_state(state, plane); > + > + if (!new_plane_state || !old_plane_state) > return; > > fb = new_plane_state->fb; -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 840 bytes --]
next prev parent reply other threads:[~2022-07-29 14:23 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-29 3:07 [PATCH] drm/kmb: fix dereference before NULL check in kmb_plane_atomic_update() Zeng Jingxiang 2022-07-29 3:07 ` Zeng Jingxiang 2022-07-29 14:23 ` Thomas Zimmermann [this message] 2022-07-29 14:23 ` Thomas Zimmermann 2022-07-29 14:25 ` Thomas Zimmermann 2022-07-29 16:40 ` Chrisanthus, Anitha 2022-08-01 10:27 ` Thomas Zimmermann
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