From: Harry Wentland <harry.wentland@amd.com> stable inclusion from stable-6.6.157 commit 4d5ee095a58461b2446d7a6eb0c14c2fe3eaab44 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19551 CVE: CVE-2026-89821 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ------------------------------ commit 4f40873f8a4107df2b9c8e68c947c4fd0cd519d2 upstream. __is_lut_linear() computes the expected value of each entry with expected = i * MAX_DRM_LUT_VALUE / (size - 1); If it is ever called with a single-entry LUT, size - 1 is zero and the kernel takes a divide error (#DE). A LUT with fewer than two entries cannot describe a linear mapping anyway, so return false early instead of dividing by zero. Fixes: 086247a4b2fb ("drm/amd/display: Use 4096 lut entries") Cc: stable@vger.kernel.org Signed-off-by: Harry Wentland <harry.wentland@amd.com> Reviewed-by: Melissa Wen <mwen@igalia.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Hulk Robot <hulkrobot@huawei.com> --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c index a4cb23d059bd..191a3c5cded5 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c @@ -118,6 +118,12 @@ static bool __is_lut_linear(const struct drm_color_lut *lut, uint32_t size) uint32_t expected; int delta; + /* A LUT with fewer than two entries can't be interpolated and would + * divide by zero below (size - 1); it can't be treated as linear. + */ + if (size < 2) + return false; + for (i = 0; i < size; i++) { /* All color values should equal */ if ((lut[i].red != lut[i].green) || (lut[i].green != lut[i].blue)) -- 2.22.0