[PATCH 0/2] drm/amdgpu,radeon: fix integer overflow in pitch alignment

[Werner Kasselman <werner@verivus.ai>]

Both amdgpu_gem_align_pitch() and radeon_align_pitch() use signed int
for the pitch calculation. When alignment rounding pushes the width to
a boundary value, 'aligned * cpp' overflows signed 32-bit int to 0.

This defeats the overflow guards in drm_mode_create_dumb() because
these drivers bypass drm_mode_size_dumb() and perform their own
alignment rounding, which can push the pitch past the pre-validated
range.

A zero pitch propagates to a zero-size GEM object allocation reachable
from unprivileged userspace via DRM_IOCTL_MODE_CREATE_DUMB on the
render node.

Both drivers need the same fix: add an overflow check in the alignment
function and reject zero pitch/size in the dumb_create callback. The
proper long-term fix is to convert both drivers to use
drm_mode_size_dumb() as Thomas Zimmermann's series is doing for other
drivers.

Werner Kasselman (2):
  drm/amdgpu: fix integer overflow in amdgpu_gem_align_pitch()
  drm/radeon: fix integer overflow in radeon_align_pitch()

 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 13 +++++++++++++
 drivers/gpu/drm/radeon/radeon_gem.c     |  9 +++++++++
 2 files changed, 22 insertions(+)

-- 
2.43.0