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@xxxxxxxxxxxxxxx # 6.1+
Fixes: 30ebe41582d1 ("drm/amd/display: add FB_DAMAGE_CLIPS support")
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
---
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;
--
2.40.1
