From: Al Viro <viro@zeniv.linux.org.uk>
To: syzbot <syzbot+5399ed0832693e29f392@syzkaller.appspotmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: kernel BUG at fs/inode.c:LINE!
Date: Mon, 17 Dec 2018 07:21:44 +0000 [thread overview]
Message-ID: <20181217072144.GQ2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <00000000000051e9c2057d31a563@google.com>
On Sun, Dec 16, 2018 at 10:11:04PM -0800, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: d14b746c6c1c Add linux-next specific files for 20181214
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=13706347400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=1da6d2d18f803140
> dashboard link: https://syzkaller.appspot.com/bug?extid=5399ed0832693e29f392
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101032b3400000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16534063400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+5399ed0832693e29f392@syzkaller.appspotmail.com
>
> slab_pre_alloc_hook mm/slab.h:423 [inline]
> slab_alloc mm/slab.c:3365 [inline]
> kmem_cache_alloc+0x2c4/0x730 mm/slab.c:3539
> __d_alloc+0xc8/0xb90 fs/dcache.c:1599
> ------------[ cut here ]------------
> kernel BUG at fs/inode.c:1566!
> d_alloc_anon fs/dcache.c:1698 [inline]
> d_make_root+0x43/0xc0 fs/dcache.c:1885
> autofs_fill_super+0x6f1/0x1c30 fs/autofs/inode.c:273
Huh? BUG is in iput(), AFAICS, so the stack trace is rather misreported.
iput() can be called by d_make_root(), provided that dentry allocation
fails. So the most straightforward interpretation would be that we
had an allocation failure (injected?), followed by iput() of the inode
passed to d_make_root(). Which happened to find I_CLEAR in ->i_state
of that inode somehow, which should be impossible short of seriously
buggered inode refcounting somewhere - the inode has just been returned
by new_inode(), which clears i_state, and it would have to have passed
clear_inode() (i.e. has been through inode eviction) since then...
next prev parent reply other threads:[~2018-12-17 7:21 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-17 6:11 kernel BUG at fs/inode.c:LINE! syzbot
2018-12-17 7:21 ` Al Viro [this message]
2018-12-17 10:08 ` Dmitry Vyukov
2018-12-18 10:40 ` Tetsuo Handa
2018-12-18 10:42 ` Ian Kent
2018-12-18 11:01 ` Amir Goldstein
2018-12-18 11:52 ` Ian Kent
2018-12-18 11:34 ` Ian Kent
2018-12-18 12:27 ` Dmitry Vyukov
2018-12-18 12:42 ` Ian Kent
2018-12-18 13:19 ` Dmitry Vyukov
2018-12-18 14:40 ` Ian Kent
2018-12-18 21:09 ` Andrew Morton
2018-12-19 0:05 ` Ian Kent
2018-12-18 13:51 ` Al Viro
2019-04-09 14:36 ` syzbot
2019-04-10 0:26 ` Al Viro
2019-04-10 8:27 ` Dmitry Vyukov
2019-04-10 10:35 ` Ian Kent
2019-04-10 11:40 ` Dmitry Vyukov
2019-04-10 11:57 ` Ian Kent
2019-04-10 12:02 ` Dmitry Vyukov
2019-04-10 12:03 ` Dmitry Vyukov
2019-04-10 12:07 ` Ian Kent
2019-04-10 12:11 ` Al Viro
2019-04-10 12:41 ` Dmitry Vyukov
2019-04-11 0:50 ` Ian Kent
2019-04-11 2:22 ` Al Viro
2019-04-12 11:04 ` Dmitry Vyukov
2019-04-12 19:46 ` Eric Biggers
2019-04-12 10:59 ` Dmitry Vyukov
2019-04-12 19:19 ` Al Viro
2019-04-10 12:39 ` Dmitry Vyukov
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