On 2/19/2018 8:32 AM, Daniel Vetter wrote:
On Mon, Feb 12, 2018 at 02:51:44PM -0500, Joe Moriarty wrote:
The Parfait (version 2.1.0) static code analysis tool found the
following NULL pointer derefernce problem.
- drivers/gpu/drm/drm_vblank.c
Null pointer checks were added to return values from calls to
drm_crtc_from_index(). There is a possibility, however minute, that
crtc->index may not be found when trying to find the struct crtc
from it's assigned index given in drm_crtc_init_with_planes().
3 return checks for NULL where added.
Signed-off-by: Joe Moriarty <joe.moriarty@xxxxxxxxxx>
Reviewed-by: Steven Sistare <steven.sistare@xxxxxxxxxx>
These are all drivers bugs, we'd need at least a WARN_ON when the crtc
doesn't exist. Otherwise this would just silently paper over a fairly
serious kernel bug (which doesn't improve things really).
Something like
if (WARN_ON(!crtc))
return NULL;
is what I'd go with.
-Daniel
I will make the requested changes and resubmit the patch. Thanks for
reviewing the patches.
Joe
---
drivers/gpu/drm/drm_vblank.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 32d9bcf5be7f..a3a1bce87468 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -120,7 +120,7 @@ static u32 __get_vblank_counter(struct drm_device *dev, unsigned int pipe)
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
- if (crtc->funcs->get_vblank_counter)
+ if (crtc && crtc->funcs->get_vblank_counter)
return crtc->funcs->get_vblank_counter(crtc);
}
@@ -318,7 +318,7 @@ static void __disable_vblank(struct drm_device *dev, unsigned int pipe)
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
- if (crtc->funcs->disable_vblank) {
+ if (crtc && crtc->funcs->disable_vblank) {
crtc->funcs->disable_vblank(crtc);
return;
}
@@ -918,7 +918,7 @@ static int __enable_vblank(struct drm_device *dev, unsigned int pipe)
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
- if (crtc->funcs->enable_vblank)
+ if (crtc && crtc->funcs->enable_vblank)
return crtc->funcs->enable_vblank(crtc);
}
--
2.15.0
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