CVE-2021-47124

In the Linux kernel, the following vulnerability has been resolved:
io_uring: fix link timeout refs WARNING: CPU: 0 PID: 10242 at
lib/refcount.c:28 refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 RIP:
0010:refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 Call Trace:
__refcount_sub_and_test include/linux/refcount.h:283 [inline]
__refcount_dec_and_test include/linux/refcount.h:315 [inline]
refcount_dec_and_test include/linux/refcount.h:333 [inline] io_put_req
fs/io_uring.c:2140 [inline] io_queue_linked_timeout fs/io_uring.c:6300
[inline] __io_queue_sqe+0xbef/0xec0 fs/io_uring.c:6354 io_submit_sqe
fs/io_uring.c:6534 [inline] io_submit_sqes+0x2bbd/0x7c50 fs/io_uring.c:6660
__do_sys_io_uring_enter fs/io_uring.c:9240 [inline]
__se_sys_io_uring_enter+0x256/0x1d60 fs/io_uring.c:9182
io_link_timeout_fn() should put only one reference of the linked timeout
request, however in case of racing with the master request’s completion
first io_req_complete() puts one and then io_put_req_deferred() is called.