Currently, it is possible for us to access memory that we shouldn't. Since, we acquire (possibly dangling) pointers to dirty rectangles before doing a bounds check to make sure we can actually accommodate the number of dirty rectangles userspace has requested to fill. This issue is especially evident if a compositor requests both MPO and damage clips at the same time, in which case I have observed a soft-hang. So, to avoid this issue, perform the bounds check before filling a single dirty rectangle and WARN() about it, if it is ever attempted in fill_dc_dirty_rect().
Cc: stable@vger.kernel.org # 6.1+ Fixes: 30ebe41582d1 ("drm/amd/display: add FB_DAMAGE_CLIPS support") Signed-off-by: Hamza Mahfooz hamza.mahfooz@amd.com --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 64b8dcf8dbda..66bb03d503ea 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -5065,11 +5065,7 @@ static inline void fill_dc_dirty_rect(struct drm_plane *plane, s32 y, s32 width, s32 height, int *i, bool ffu) { - if (*i > DC_MAX_DIRTY_RECTS) - return; - - if (*i == DC_MAX_DIRTY_RECTS) - goto out; + WARN_ON(*i >= DC_MAX_DIRTY_RECTS);
dirty_rect->x = x; dirty_rect->y = y; @@ -5085,7 +5081,6 @@ static inline void fill_dc_dirty_rect(struct drm_plane *plane, "[PLANE:%d] PSR SU dirty rect at (%d, %d) size (%d, %d)", plane->base.id, x, y, width, height);
-out: (*i)++; }
@@ -5172,6 +5167,9 @@ static void fill_dc_dirty_rects(struct drm_plane *plane,
*dirty_regions_changed = bb_changed;
+ if ((num_clips + (bb_changed ? 2 : 0)) > DC_MAX_DIRTY_RECTS) + goto ffu; + if (bb_changed) { fill_dc_dirty_rect(new_plane_state->plane, &dirty_rects[i], new_plane_state->crtc_x, @@ -5201,9 +5199,6 @@ static void fill_dc_dirty_rects(struct drm_plane *plane, new_plane_state->crtc_h, &i, false); }
- if (i > DC_MAX_DIRTY_RECTS) - goto ffu; - flip_addrs->dirty_rect_count = i; return;