linux-kernel - Re: [PATCH?] reiserfs: prevent panic: don't allow %-char in journal dev. name

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Date:   Mon, 9 Apr 2018 16:30:49 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Jeff Mahoney <jeffm@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        reiserfs-devel@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jan Kara <jack@...e.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Artem Bityutskiy <dedekind1@...il.com>,
        syzkaller-bugs@...glegroups.com,
        syzbot+6bd77b88c1977c03f584@...kaller.appspotmail.com
Subject: Re: [PATCH?] reiserfs: prevent panic: don't allow %-char in journal
 dev. name

On Mon, Apr 9, 2018 at 4:25 PM, Jan Kara <jack@...e.cz> wrote:
> On Wed 04-04-18 21:48:53, Jeff Mahoney wrote:
>> On 4/4/18 9:45 PM, Andrew Morton wrote:
>> > On Wed, 4 Apr 2018 18:25:16 -0700 Randy Dunlap <rdunlap@...radead.org> wrote:
>> >
>> >> From: Randy Dunlap <rdunlap@...radead.org>
>> >>
>> >> If the reiserfs mount option's journal name contains a '%' character,
>> >> it can lead to a WARN_ONCE() in lib/vsprintf.c::format_decode(),
>> >> saying: "Please remove unsupported %/ in format string."
>> >> That's OK until panic_on_warn is set, at which point it's dead, Jim.
>> >>
>> >> To placate this situation, check the journal name string for a '%'
>> >> character and return an error if one is found. Also print a warning
>> >> (one that won't panic the kernel) about the invalid journal name (e.g.):
>> >>
>> >>   reiserfs: journal device name is invalid: %/file0
>> >>
>> >> (In this example, the caller app specified the journal device name as
>> >> "%/file0".)
>> >>
>> >
>> > Well, that is a valid filename and we should support it...
>> >
>> > Isn't the bug in journal_init_dev()?
>>
>> Yep.  That's exactly it.
>>
>> Acked-by: Jeff Mahoney <jeffm@...e.com>
>
> Thanks. I've picked up the patch from Andrew, added his Signed-off-by (OK,
> Andrew?), wrote a proper changelog and pushed it to my tree. The result is
> attached.

Hi Jan,

Please also add:

Reported-by: syzbot+6bd77b88c1977c03f584@...kaller.appspotmail.com

as the original reporter.