linux-kernel - [PATCH] drm/amdgpu: Fix integer overflow issues in amdgpu_userq

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Message-ID: <aDCc5kawU4cWj-Cx@stanley.mountain>
Date: Fri, 23 May 2025 19:05:58 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@....com>
Cc: Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Arvind Yadav <Arvind.Yadav@....com>,
	Shashank Sharma <shashank.sharma@....com>,
	amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] drm/amdgpu: Fix integer overflow issues in
 amdgpu_userq_fence.c

This patch only affects 32bit systems.  There are several integer
overflows bugs here but only the "sizeof(u32) * num_syncobj"
multiplication is a problem at runtime.  (The last lines of this patch).

These variables are u32 variables that come from the user.  The issue
is the multiplications can overflow leading to us allocating a smaller
buffer than intended.  For the first couple integer overflows, the
syncobj_handles = memdup_user() allocation is immediately followed by
a kmalloc_array():

	syncobj = kmalloc_array(num_syncobj_handles, sizeof(*syncobj), GFP_KERNEL);

In that situation the kmalloc_array() works as a bounds check and we
haven't accessed the syncobj_handlesp[] array yet so the integer overflow
is harmless.

But the "num_syncobj" multiplication doesn't have that and the integer
overflow could lead to an out of bounds access.

Fixes: a292fdecd728 ("drm/amdgpu: Implement userqueue signal/wait IOCTL")
Cc: stable@...r.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
index 029cb24c28b3..bd79f105d77f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
@@ -430,7 +430,7 @@ int amdgpu_userq_signal_ioctl(struct drm_device *dev, void *data,
 
 	num_syncobj_handles = args->num_syncobj_handles;
 	syncobj_handles = memdup_user(u64_to_user_ptr(args->syncobj_handles),
-				      sizeof(u32) * num_syncobj_handles);
+				      size_mul(sizeof(u32), num_syncobj_handles));
 	if (IS_ERR(syncobj_handles))
 		return PTR_ERR(syncobj_handles);
 
@@ -612,13 +612,13 @@ int amdgpu_userq_wait_ioctl(struct drm_device *dev, void *data,
 
 	num_read_bo_handles = wait_info->num_bo_read_handles;
 	bo_handles_read = memdup_user(u64_to_user_ptr(wait_info->bo_read_handles),
-				      sizeof(u32) * num_read_bo_handles);
+				      size_mul(sizeof(u32), num_read_bo_handles));
 	if (IS_ERR(bo_handles_read))
 		return PTR_ERR(bo_handles_read);
 
 	num_write_bo_handles = wait_info->num_bo_write_handles;
 	bo_handles_write = memdup_user(u64_to_user_ptr(wait_info->bo_write_handles),
-				       sizeof(u32) * num_write_bo_handles);
+				       size_mul(sizeof(u32), num_write_bo_handles));
 	if (IS_ERR(bo_handles_write)) {
 		r = PTR_ERR(bo_handles_write);
 		goto free_bo_handles_read;
@@ -626,7 +626,7 @@ int amdgpu_userq_wait_ioctl(struct drm_device *dev, void *data,
 
 	num_syncobj = wait_info->num_syncobj_handles;
 	syncobj_handles = memdup_user(u64_to_user_ptr(wait_info->syncobj_handles),
-				      sizeof(u32) * num_syncobj);
+				      size_mul(sizeof(u32), num_syncobj));
 	if (IS_ERR(syncobj_handles)) {
 		r = PTR_ERR(syncobj_handles);
 		goto free_bo_handles_write;
-- 
2.47.2