block: fix single bio async DIO error handling

BUG: KASAN: use-after-free in io_submit_one+0x496/0x2fe0 fs/aio.c:1882
CPU: 2 PID: 15100 Comm: syz-executor873 Not tainted 5.16.0-rc1-syzk #1
Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29
04/01/2014
Call Trace:
  [...]
  refcount_dec_and_test include/linux/refcount.h:333 [inline]
  iocb_put fs/aio.c:1161 [inline]
  io_submit_one+0x496/0x2fe0 fs/aio.c:1882
  __do_sys_io_submit fs/aio.c:1938 [inline]
  __se_sys_io_submit fs/aio.c:1908 [inline]
  __x64_sys_io_submit+0x1c7/0x4a0 fs/aio.c:1908
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x44/0xae

__blkdev_direct_IO_async() returns errors from bio_iov_iter_get_pages()
directly, in which case upper layers won't be expecting ->ki_complete
to be called by the block layer and will terminate the request. However,
there is also bio_endio() leading to a second ->ki_complete and a double
free.

Fixes: 54a88eb838 ("block: add single bio async direct IO helper")
Reported-by: George Kennedy <george.kennedy@oracle.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c9eb786f6cef041e159e6287de131bec0719ad5c.1638907997.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/fops.c

@@ -340,8 +340,7 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
 	} else {
 		ret = bio_iov_iter_get_pages(bio, iter);
 		if (unlikely(ret)) {
-			bio->bi_status = BLK_STS_IOERR;
-			bio_endio(bio);
+			bio_put(bio);
 			return ret;
 		}
 	}