[PATCH 6.6.y 2/2] drm/amdgpu: Limit BO list entry count to prevent resource exhaustion

[PATCH 6.6.y 2/2] drm/amdgpu: Limit BO list entry count to prevent resource exhaustion

[Fang Wang]

From: "Jesse.Zhang" <Jesse.Zhang@amd.com>

[ Upstream commit 6270b1a5dab94665d7adce3dc78bc9066ed28bdd ]

Userspace can pass an arbitrary number of BO list entries via the
bo_number field. Although the previous multiplication overflow check
prevents out-of-bounds allocation, a large number of entries could still
cause excessive memory allocation (up to potentially gigabytes) and
unnecessarily long list processing times.

Introduce a hard limit of 128k entries per BO list, which is more than
sufficient for any realistic use case (e.g., a single list containing all
buffers in a large scene). This prevents memory exhaustion attacks and
ensures predictable performance.

Return -EINVAL if the requested entry count exceeds the limit

Reviewed-by: Christian König <christian.koenig@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jesse Zhang <jesse.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 688b87d39e0aa8135105b40dc167d74b5ada5332)
Cc: stable@vger.kernel.org
Signed-off-by: Fang Wang <32840572@qq.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
index db0a1c828fe1..4efdc49d1015 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
@@ -36,6 +36,7 @@
 
 #define AMDGPU_BO_LIST_MAX_PRIORITY	32u
 #define AMDGPU_BO_LIST_NUM_BUCKETS	(AMDGPU_BO_LIST_MAX_PRIORITY + 1)
+#define AMDGPU_BO_LIST_MAX_ENTRIES	(128 * 1024)
 
 static void amdgpu_bo_list_free_rcu(struct rcu_head *rcu)
 {
@@ -201,6 +202,9 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
 	const uint32_t bo_number = in->bo_number;
 	struct drm_amdgpu_bo_list_entry *info;
 
+	if (bo_number > AMDGPU_BO_LIST_MAX_ENTRIES)
+		return -EINVAL;
+
 	/* copy the handle array from userspace to a kernel buffer */
 	if (likely(info_size == bo_info_size)) {
 		info = vmemdup_array_user(uptr, bo_number, info_size);
-- 
2.34.1