io_uring/sqpoll: work around a potential audit memory leak

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/sqpoll: work around a potential audit memory leak kmemleak complains that there's a memory leak related to connect handling: unreferenced object 0xffff0001093bdf00 (size 128): comm "iou-sqp-455", pid 457, jiffies 4294894164 hex dump (first 32 bytes): 02 00 fa ea 7f 00 00 01 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 2e481b1a): [<00000000c0a26af4>] kmemleak_alloc+0x30/0x38 [<000000009c30bb45>] kmalloc_trace+0x228/0x358 [<000000009da9d39f>] __audit_sockaddr+0xd0/0x138 [<0000000089a93e34>] move_addr_to_kernel+0x1a0/0x1f8 [<000000000b4e80e6>] io_connect_prep+0x1ec/0x2d4 [<00000000abfbcd99>] io_submit_sqes+0x588/0x1e48 [<00000000e7c25e07>] io_sq_thread+0x8a4/0x10e4 [<00000000d999b491>] ret_from_fork+0x10/0x20 which can can happen if: 1) The command type does something on the prep side that triggers an audit call. 2) The thread hasn't done any operations before this that triggered an audit call inside ->issue(), where we have audit_uring_entry() and audit_uring_exit(). Work around this by issuing a blanket NOP operation before the SQPOLL does anything.

References

• https://git.kernel.org/stable/c/55c22375cbaa24f77dd13f9ae0642915444a1227
• https://git.kernel.org/stable/c/9e810bd995823786ea30543e480e8a573e5e5667
• https://git.kernel.org/stable/c/a40e90d9304629002fb17200f7779823a81191d3
• https://git.kernel.org/stable/c/c4ce0ab27646f4206a9eb502d6fe45cb080e1cae