| Message ID | 20211130144827.163717-1-zhou1615@umn.edu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/radeon/radeon_connectors: Fix a NULL pointer dereference in radeon_fp_native_mode() | expand |
On Tue, Nov 30, 2021 at 9:49 AM Zhou Qingyang <zhou1615@umn.edu> wrote: > > In radeon_fp_native_mode(), the return value of drm_mode_duplicate() is > assigned to mode and there is a dereference of it in > radeon_fp_native_mode(), which could lead to a NULL pointer > dereference on failure of drm_mode_duplicate(). > > Fix this bug by adding a check of mode. > > This bug was found by a static analyzer. The analysis employs > differential checking to identify inconsistent security operations > (e.g., checks or kfrees) between two code paths and confirms that the > inconsistent operations are not recovered in the current function or > the callers, so they constitute bugs. > > Note that, as a bug found by static analysis, it can be a false > positive or hard to trigger. Multiple researchers have cross-reviewed > the bug. > > Builds with CONFIG_DRM_RADEON=m show no new warnings, > and our static analyzer no longer warns about this code. > > Fixes: d2efdf6d6f42 ("drm/radeon/kms: add cvt mode if we only have lvds w/h and no edid (v4)") > Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> > --- > drivers/gpu/drm/radeon/radeon_connectors.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c > index 607ad5620bd9..49f187614f96 100644 > --- a/drivers/gpu/drm/radeon/radeon_connectors.c > +++ b/drivers/gpu/drm/radeon/radeon_connectors.c > @@ -473,6 +473,9 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode > native_mode->vdisplay != 0 && > native_mode->clock != 0) { > mode = drm_mode_duplicate(dev, native_mode); > + if (!mode) > + return NULL; > + The else if clause needs a similar check. Care to fix that up as well? Alex > mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER; > drm_mode_set_name(mode); > > -- > 2.25.1 >
diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c index 607ad5620bd9..49f187614f96 100644 --- a/drivers/gpu/drm/radeon/radeon_connectors.c +++ b/drivers/gpu/drm/radeon/radeon_connectors.c @@ -473,6 +473,9 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode native_mode->vdisplay != 0 && native_mode->clock != 0) { mode = drm_mode_duplicate(dev, native_mode); + if (!mode) + return NULL; + mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER; drm_mode_set_name(mode);
In radeon_fp_native_mode(), the return value of drm_mode_duplicate() is assigned to mode and there is a dereference of it in radeon_fp_native_mode(), which could lead to a NULL pointer dereference on failure of drm_mode_duplicate(). Fix this bug by adding a check of mode. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_DRM_RADEON=m show no new warnings, and our static analyzer no longer warns about this code. Fixes: d2efdf6d6f42 ("drm/radeon/kms: add cvt mode if we only have lvds w/h and no edid (v4)") Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> --- drivers/gpu/drm/radeon/radeon_connectors.c | 3 +++ 1 file changed, 3 insertions(+)