linux-kernel - [PATCH] drm/amdgpu: check num_entries in GEM_OP GET_MAPPING

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Message-Id: <20260208000255.4073363-1-n7l8m4@u.northwestern.edu>
Date: Sun,  8 Feb 2026 00:02:55 +0000
From: Ziyi Guo <n7l8m4@...orthwestern.edu>
To: Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>
Cc: David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Ziyi Guo <n7l8m4@...orthwestern.edu>
Subject: [PATCH] drm/amdgpu: check num_entries in GEM_OP GET_MAPPING_INFO

kvcalloc(args->num_entries, sizeof(*vm_entries), GFP_KERNEL) at
amdgpu_gem.c:1050 uses the user-supplied num_entries directly without
any upper bounds check. Since num_entries is a __u32 and
sizeof(drm_amdgpu_gem_vm_entry) is 32 bytes, a large num_entries
produces an allocation exceeding INT_MAX, triggering
WARNING in __kvmalloc_node_noprof(), causing a kernel WARNING,
TAINT_WARN, and panic on CONFIG_PANIC_ON_WARN=y systems.

Add a size bounds check before we invoke the kvzalloc() to
reject oversized num_entries early with -EINVAL.

Fixes: 4d82724f7f2b ("drm/amdgpu: Add mapping info option for GEM_OP ioctl")
Signed-off-by: Ziyi Guo <n7l8m4@...orthwestern.edu>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 3e38c5db2987..ef5d8bd216b2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -1047,6 +1047,11 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
 		 * If that number is larger than the size of the array, the ioctl must
 		 * be retried.
 		 */
+		if (args->num_entries > INT_MAX / sizeof(*vm_entries)) {
+			r = -EINVAL;
+			goto out_exec;
+		}
+
 		vm_entries = kvcalloc(args->num_entries, sizeof(*vm_entries), GFP_KERNEL);
 		if (!vm_entries)
 			return -ENOMEM;
-- 
2.34.1