[PATCH] drm/amdgpu: Fix integer overflow issues in amdgpu_userq_fence.c

[Alex Deucher]

Applied.  Thanks!

On Fri, May 23, 2025 at 12:25 PM Dan Carpenter <dan.carpenter at linaro.org> wrote:
>
> 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 at vger.kernel.org
> Signed-off-by: Dan Carpenter <dan.carpenter at linaro.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
>