This is a note to let you know that I've just added the patch titled
io_uring: Clean up a false-positive warning from GCC 9.3.0
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-clean-up-a-false-positive-warning-from-gcc-9.3.0.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f79aabb5fcef594b03b9c7d790640833d95b0604 Mon Sep 17 00:00:00 2001
From: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxx>
Date: Mon, 7 Feb 2022 21:05:33 +0700
Subject: io_uring: Clean up a false-positive warning from GCC 9.3.0
From: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxx>
commit 0d7c1153d9291197c1dc473cfaade77acb874b4b upstream.
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@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reported-by: "Chen, Rong A" <rong.a.chen@xxxxxxxxx>
Link: https://lore.gnuweeb.org/timl/d33bb5a9-8173-f65b-f653-51fc0681c6d6@xxxxxxxxx/
Cc: Pavel Begunkov <asml.silence@xxxxxxxxx>
Suggested-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
Fixes: 7297ce3d59449de49d3c9e1f64ae25488750a1fc ("io_uring: improve send/recv error handling")
Signed-off-by: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxx>
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220207140533.565411-1-ammarfaizi2@xxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -5094,7 +5094,6 @@ static int io_recv(struct io_kiocb *req,
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;
@@ -5109,6 +5108,7 @@ out_free:
}
req_set_fail(req);
} else if ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
+out_free:
req_set_fail(req);
}
if (req->flags & REQ_F_BUFFER_SELECTED)
Patches currently in stable-queue which might be from alviro.iskandar@xxxxxxxxx are
queue-5.10/io_uring-clean-up-a-false-positive-warning-from-gcc-9.3.0.patch
