Re: [PATCH] drm/amdkfd: fix NULL dereference in get_queue_ids()

[Alex Deucher]

Applied.  Thanks!

Alex

On Mon, May 25, 2026 at 5:59 AM Muhammad Bilal <meatuni001@xxxxxxxxx> wrote:
>
> When usr_queue_id_array is NULL and num_queues is non-zero,
> get_queue_ids() returns NULL. The callers check only IS_ERR() on the
> return value; since IS_ERR(NULL) == false the check passes, and
> suspend_queues() calls q_array_invalidate() which immediately
> dereferences NULL while iterating num_queues times.
>
> Userspace can trigger this via kfd_ioctl_set_debug_trap() by supplying
> num_queues > 0 with a zero queue_array_ptr, causing a kernel panic.
>
> A NULL usr_queue_id_array with num_queues == 0 is a legitimate no-op
> (q_array_invalidate never executes, and resume_queues already guards
> all queue_ids dereferences behind a NULL check). Return ERR_PTR(-EINVAL)
> only when num_queues is non-zero and the pointer is absent; both callers
> already propagate IS_ERR() returns correctly to userspace.
>
> Fixes: a70a93fa568b ("drm/amdkfd: add debug suspend and resume process queues operation")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Muhammad Bilal <meatuni001@xxxxxxxxx>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> index c08ad718dbd7..8488b3a6c2ba 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> @@ -3312,7 +3312,7 @@ static uint32_t *get_queue_ids(uint32_t num_queues, uint32_t *usr_queue_id_array
>         size_t array_size;
>
>         if (!usr_queue_id_array)
> -               return NULL;
> +               return num_queues ? ERR_PTR(-EINVAL) : NULL;
>
>         if (check_mul_overflow((size_t)num_queues, sizeof(uint32_t), &array_size))
>                 return ERR_PTR(-EINVAL);
> --
> 2.53.0
>