From: Jens Axboe <[email protected]>
To: Ammar Faizi <[email protected]>
Cc: GNU/Weeb Mailing List <[email protected]>,
io-uring Mailing list <[email protected]>,
Tea Inside Mailing List <[email protected]>,
Linux Kernel Mailing List <[email protected]>,
Alviro Iskandar Setiawan <[email protected]>,
kernel test robot <[email protected]>,
Dan Carpenter <[email protected]>,
"Chen, Rong A" <[email protected]>,
Pavel Begunkov <[email protected]>
Subject: Re: [PATCH io_uring-5.17] io_uring: Fix build error potential reading uninitialized value
Date: Mon, 7 Feb 2022 06:45:57 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 2/7/22 4:43 AM, Ammar Faizi wrote:
> From: Alviro Iskandar Setiawan <[email protected]>
>
> 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.
The compiler should be able to deduce this, and I guess newer compilers
do which is why we haven't seen this warning before. I'm fine with doing
this as a cleanup, but I think the commit title should be modified a
bit. It sounds like there might be an issue reading uninitialized data,
which isn't actually true.
--
Jens Axboe
next prev parent reply other threads:[~2022-02-07 14:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[email protected]>
2022-02-07 11:43 ` [PATCH io_uring-5.17] io_uring: Fix build error potential reading uninitialized value Ammar Faizi
2022-02-07 13:45 ` Jens Axboe [this message]
2022-02-07 14:05 ` [PATCH io_uring-5.17 v2] io_uring: Clean up a false-positive warning from GCC 9.3.0 Ammar Faizi
2022-02-07 15:38 ` Jens Axboe
2022-02-07 14:20 ` [PATCH io_uring-5.17] io_uring: Fix build error potential reading uninitialized value Dan Carpenter
2022-02-07 14:33 ` Alviro Iskandar Setiawan
2022-02-07 15:37 ` Jens Axboe
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