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drm/amd/display: avoid divide-by-zero in __is_lut_linear()

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__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: 086247a4b2 ("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>
This commit is contained in:
Harry Wentland
2026-08-04 17:04:04 -04:00
committed by Alex Deucher
parent 0e4ef0ead6
commit 4f40873f8a
1 changed files with 6 additions and 0 deletions
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6
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
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@@ -471,6 +471,12 @@ 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))