[PATCH v2] drm/radeon: fix integer overflow in radeon_align_pitch()

Werner Kasselman
2026-04-14T21:14:44Z

radeon_align_pitch() has the same kind of overflow issue as the old
amdgpu helper: the alignment round-up add and the final 'aligned * cpp'
calculation can overflow signed int.

If that wraps to 0, radeon_mode_dumb_create() can end up with an invalid
pitch value from DRM_IOCTL_MODE_CREATE_DUMB.

Fix this by using check_add_overflow() for the alignment round-up and
check_mul_overflow() for the final pitch calculation, returning 0 on
overflow.

Found via AST-based call-graph analysis using sqry.

Fixes: ff72145badb8 ("drm: dumb scanout create/mmap for intel/radeon (v3)")
Cc: stable@vger.kernel.org
Signed-off-by: Werner Kasselman <werner@verivus.com>
---
v2:
- Use overflow helpers like amdgpu.
- Drop the stale zero pitch/size change from the original submission.
- Fix the changelog wording around reachability.

drivers/gpu/drm/radeon/radeon_gem.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 2cd179fef347..8ce180e22d1d 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -28,6 +28,7 @@

#include <linux/debugfs.h>
#include <linux/iosys-map.h>
+#include <linux/overflow.h>
#include <linux/pci.h>

#include <drm/drm_device.h>
@@ -812,6 +813,7 @@ int radeon_align_pitch(struct radeon_device *rdev, int width, int cpp, bool tile
int aligned = width;
int align_large = (ASIC_IS_AVIVO(rdev)) || tiled;
int pitch_mask = 0;
+ int pitch;

switch (cpp) {
case 1:
@@ -826,14 +828,12 @@ int radeon_align_pitch(struct radeon_device *rdev, int width, int cpp, bool tile
break;
}

- aligned += pitch_mask;
+ if (check_add_overflow(aligned, pitch_mask, &aligned))
+ return 0;
aligned &= ~pitch_mask;
-
- /* Guard against integer overflow in aligned * cpp. */
- if (aligned > INT_MAX / (cpp ? cpp : 1) || aligned <= 0)
+ if (check_mul_overflow(aligned, cpp, &pitch))
return 0;
-
- return aligned * cpp;
+ return pitch;
}

int radeon_mode_dumb_create(struct drm_file *file_priv,
--
2.43.0