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.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index 3983708cef5b431789e0dee10592b73952f7a4e5..554c7212aa4631664f04184d2b3fc6e2b14a4085 100644 (file)
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -291,6 +291,14 @@ static int io_sq_thread(void *data)
                sqd->sq_cpu = raw_smp_processor_id();
        }
 
+       /*
+        * Force audit context to get setup, in case we do prep side async
+        * operations that would trigger an audit call before any issue side
+        * audit has been done.
+        */
+       audit_uring_entry(IORING_OP_NOP);
+       audit_uring_exit(true, 0);
+
        mutex_lock(&sqd->lock);
        while (1) {
                bool cap_entries, sqt_spin = false;