drm/amd/display: Fix integer overflow in bios_get_image()

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commit cd86529ec6 upstream.

[Why&How]
The bounds check in bios_get_image() computes 'offset + size' using
unsigned 32-bit arithmetic before comparing against bios_size. If a
VBIOS image contains a near-UINT32_MAX offset the addition wraps to a
small value, the comparison passes, and the function returns a wild
pointer past the VBIOS mapping.

Additionally, the comparison uses '<' (strict), which incorrectly
rejects the valid exact-fit case where offset + size == bios_size.

Fix both issues by restructuring the check to avoid the addition
entirely: first reject if offset alone exceeds bios_size, then check
size against the remaining space (bios_size - offset). This eliminates
the overflow and correctly permits exact-fit accesses.

Assisted-by: GitHub Copilot:claude-opus-4.6
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit d40fb392af)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Harry Wentland 2026-05-04 11:14:45 -04:00 • committed by Greg Kroah-Hartman

parent b28cf21422

commit 8903f28b28

1 changed files with 6 additions and 3 deletions

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drivers/gpu/drm/amd/display/dc/bios/bios_parser_helper.c

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