linux-kernel - Re: [PATCH] tmpfs: fix uninitialized return value in shmem

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Message-ID: <20190226002904.GE6474@magnolia>
Date:   Mon, 25 Feb 2019 16:29:04 -0800
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Qian Cai <cai@....pw>, Hugh Dickins <hughd@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matej Kupljen <matej.kupljen@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH] tmpfs: fix uninitialized return value in shmem_link

On Mon, Feb 25, 2019 at 04:07:12PM -0800, Linus Torvalds wrote:
> On Mon, Feb 25, 2019 at 4:03 PM Qian Cai <cai@....pw> wrote:
> > >
> > > Of course, that's just gcc. I have no idea what llvm ends up doing.
> >
> > Clang 7.0:
> >
> > # clang  -O2 -S -Wall /tmp/test.c
> > /tmp/test.c:46:6: warning: variable 'ret' is used uninitialized whenever 'if'
> > condition is false [-Wsometimes-uninitialized]
> 
> Ok, good.
> 
> Do we have any clang builds in any of the zero-day robot
> infrastructure or something? Should we?
> 
> And maybe this was how Dan noticed the problem in the first place? Or
> is it just because of his eagle-eyes?

He didn't say specifically how he found it, but I would guess he was
running smatch...?

--D

>                   Linus