CVE-2022-50726CVE-2022-50726

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix possible use-after-free in async command interface mlx5_cmd_cleanup_async_ctx should return only after all its callback handlers were completed. Before this patch, the below race between mlx5_cmd_cleanup_async_ctx and mlx5_cmd_exec_cb_handler was possible and lead to a use-after-free: 1. mlx5_cmd_cleanup_async_ctx is called while num_inflight is 2 (i.e. elevated by 1, a single inflight callback). 2. mlx5_cmd_cleanup_async_ctx decreases num_inflight to 1. 3. mlx5_cmd_exec_cb_handler is called, decreases num_inflight to 0 and is about to call wake_up(). 4. mlx5_cmd_cleanup_async_ctx calls wait_event, which returns immediately as the condition (num_inflight == 0) holds. 5. mlx5_cmd_cleanup_async_ctx returns. 6. The caller of mlx5_cmd_cleanup_async_ctx frees the mlx5_async_ctx object. 7. mlx5_cmd_exec_cb_handler goes on and calls wake_up() on the freed object. Fix it by syncing using a comp