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io_uring: Clean up a false-positive warning from GCC 9.3.0

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In io_recv(), if import_single_range() fails, the @flags variable is
uninitialized, then it will goto out_free.

After the goto, the compiler doesn't know that (ret < min_ret) is
always true, so it thinks the "if ((flags & MSG_WAITALL) ..."  path
could be taken.

The complaint comes from gcc-9 (Debian 9.3.0-22) 9.3.0:
```
  fs/io_uring.c:5238 io_recvfrom() error: uninitialized symbol 'flags'
```
Fix this by bypassing the @ret and @flags check when
import_single_range() fails.

Reasons:
 1. import_single_range() only returns -EFAULT when it fails.
 2. At that point, @flags is uninitialized and shouldn't be read.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: "Chen, Rong A" <rong.a.chen@intel.com>
Link: https://lore.gnuweeb.org/timl/d33bb5a9-8173-f65b-f653-51fc0681c6d6@intel.com/
Cc: Pavel Begunkov <asml.silence@gmail.com>
Suggested-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Fixes: 7297ce3d59 ("io_uring: improve send/recv error handling")
Signed-off-by: Alviro Iskandar Setiawan <alviro.iskandar@gmail.com>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Link: https://lore.kernel.org/r/20220207140533.565411-1-ammarfaizi2@gnuweeb.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Alviro Iskandar Setiawan 2022-02-07 21:05:33 +07:00 • committed by Jens Axboe
parent f6133fbd37
commit 0d7c1153d9
1 changed files with 1 additions and 2 deletions
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3
fs/io_uring.c
View file

@ -5228,7 +5228,6 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
min_ret = iov_iter_count(&msg.msg_iter);
ret = sock_recvmsg(sock, &msg, flags);
out_free:
if (ret < min_ret) {
if (ret == -EAGAIN && force_nonblock)
return -EAGAIN;
@ -5236,9 +5235,9 @@ out_free:
ret = -EINTR;
req_set_fail(req);
} else if ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
out_free:
req_set_fail(req);
}
__io_req_complete(req, issue_flags, ret, io_put_kbuf(req));
return 0;
}