[PATCH 5.10.y] drm/amd/display: Use krealloc_array() in dal_vector_reserve()

[Sasha Levin <sashal@kernel.org>]

From: Harry Wentland <harry.wentland@amd.com>

[ Upstream commit da48bc4461b8a5ebfb9264c9b191a701d8e99009 ]

[Why & How]
dal_vector_reserve() computes the allocation size as
"capacity * vector->struct_size" using uint32_t arithmetic, which can
silently wrap to a small value on overflow. This would cause krealloc to
return a smaller buffer than expected, leading to heap overflows on
subsequent vector appends.

Replace krealloc() with krealloc_array() which performs an internal
overflow check and returns NULL on wrap, preventing the issue.

Fixes: 2004f45ef83f ("drm/amd/display: Use kernel alloc/free")
Assisted-by: 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: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 37668568641ccc4cc1dbca4923d0a16609dd5707)
Cc: stable@vger.kernel.org
[ changed `krealloc_array(p, capacity, struct_size)` to `krealloc(p, array_size(capacity, struct_size))` since krealloc_array() is absent in 5.10 ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/dc/basics/vector.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/basics/vector.c b/drivers/gpu/drm/amd/display/dc/basics/vector.c
index 8f93d25f91ee2b..68c34a4e253ac1 100644
--- a/drivers/gpu/drm/amd/display/dc/basics/vector.c
+++ b/drivers/gpu/drm/amd/display/dc/basics/vector.c
@@ -292,7 +292,7 @@ bool dal_vector_reserve(struct vector *vector, uint32_t capacity)
 		return true;
 
 	new_container = krealloc(vector->container,
-				 capacity * vector->struct_size, GFP_KERNEL);
+				 array_size(capacity, vector->struct_size), GFP_KERNEL);
 
 	if (new_container) {
 		vector->container = new_container;
-- 
2.53.0