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

[Muhammad Bilal <meatuni001@gmail.com>]

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@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
---
 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