From: Hugh Dickins <hughd@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Matej Kupljen <matej.kupljen@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Dan Carpenter <dan.carpenter@oracle.com>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH] tmpfs: fix uninitialized return value in shmem_link
Date: Mon, 25 Feb 2019 12:34:21 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.2.11.1902251214220.8973@eggly.anvils> (raw)
In-Reply-To: <CAHk-=wgO3MPjPpf_ARyW6zpwwPZtxXYQgMLbmj2bnbOLnR+6Cg@mail.gmail.com>
On Mon, 25 Feb 2019, Linus Torvalds wrote:
> On Fri, Feb 22, 2019 at 10:35 PM Hugh Dickins <hughd@google.com> wrote:
> >
> > When we made the shmem_reserve_inode call in shmem_link conditional, we
> > forgot to update the declaration for ret so that it always has a known
> > value. Dan Carpenter pointed out this deficiency in the original patch.
>
> Applied.
Thanks. And I apologize for letting that slip through: Darrick sent
the patch fragment, I dressed it up, and more or less tricked him into
taking ownership of the bug, when it's I who should have been more careful.
But I'm glad it confirmed your rc8 instinct, rather than messing final :)
>
> Side note: how come gcc didn't warn about this? Yes, we disable that
> warning for some cases because of lots of false positives, but I
> thought the *default* setup still had it.
I thought so too, and have been puzzled by it. If I try removing the
initialization of inode from the next function, shmem_unlink(), I do
get the expected warning for that.
>
> Is it just that the goto ends up confusing gcc enough that it never notices?
Since the goto route did have ret properly initialized, I don't see
why it might have been confusing, but what do I know...
I thought it might be because outside the goto route, ret was used
for nothing but the return value. But that's disproved: I tried a
very silly "inode->i_flags = ret;" just after d_instantiate(),
and still no warning when ret is uninitialized.
Seems like a gcc bug? But I don't have a decent recent gcc to hand
to submit a proper report, hope someone else can shed light on it.
Hugh
next prev parent reply other threads:[~2019-02-25 20:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-21 22:21 [PATCH] tmpfs: fix uninitialized return value in shmem_link Darrick J. Wong
2019-02-21 23:05 ` Hugh Dickins
2019-02-23 6:35 ` Hugh Dickins
2019-02-25 19:53 ` Linus Torvalds
2019-02-25 20:34 ` Hugh Dickins [this message]
2019-02-25 22:34 ` Linus Torvalds
2019-02-25 23:58 ` Linus Torvalds
2019-02-26 0:03 ` Qian Cai
2019-02-26 0:07 ` Linus Torvalds
2019-02-26 0:29 ` Darrick J. Wong
2019-02-27 14:09 ` Qian Cai
2019-02-27 20:12 ` Qian Cai
2019-02-28 8:56 ` Nathan Chancellor
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