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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller <syzkaller@googlegroups.com>,
	"Kostya Serebryany" <kcc@google.com>,
	"Alexander Potapenko" <glider@google.com>,
	"Sasha Levin" <sasha.levin@oracle.com>
Subject: Re: fs: NULL deref in atime_needs_update
Date: Sat, 20 Feb 2016 03:54:43 +0000	[thread overview]
Message-ID: <20160220035442.GE17997@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20160220032127.GA19926@ZenIV.linux.org.uk>

On Sat, Feb 20, 2016 at 03:21:27AM +0000, Al Viro wrote:
> On Fri, Feb 19, 2016 at 08:32:10PM +0100, Dmitry Vyukov wrote:
> > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
> 
> NULL inode->i_sb, by the look of the offset, but I really don't understand
> where the hell is that code doing (or how is that instruction going to
> generate dereferencing of 0x50, for that matter).

BTW, Micka�l's trace *does* make sense and it's definitely NULL inode->i_sb
(inode itself - in %rsi, inode->i_sb - in %rdx, offset of s_flags is 0x50,
the line in question is
        if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))

What I don't understand is what could possibly have NULL ->i_sb in *any*
instance of struct inode.

  reply	other threads:[~2016-02-20  3:54 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-05 21:11 fs: NULL deref in atime_needs_update Dmitry Vyukov
2016-02-16 23:40 ` Mickaël Salaün
2016-02-19 19:32   ` Dmitry Vyukov
2016-02-20  3:21     ` Al Viro
2016-02-20  3:54       ` Al Viro [this message]
2016-02-20 13:25         ` Mickaël Salaün
2016-02-20 17:10           ` Al Viro
2016-02-20 20:26             ` Mickaël Salaün
2016-02-20 20:50               ` Al Viro
2016-02-22 11:20             ` Dmitry Vyukov
2016-02-22 17:23               ` Al Viro
2016-02-23 15:34                 ` Dmitry Vyukov
2016-02-23 18:17                   ` Al Viro
2016-02-20 10:36       ` Dmitry Vyukov
2016-02-24  3:12   ` Ian Kent
2016-02-24  4:46     ` Al Viro
2016-02-24 10:03       ` Dmitry Vyukov
2016-02-24 10:15         ` Dmitry Vyukov
2016-02-24 13:35           ` Dmitry Vyukov
2016-02-24 15:15             ` Al Viro
2016-02-25  8:29               ` Dmitry Vyukov
2016-02-25 16:39                 ` Al Viro
2016-02-26 21:21                   ` Al Viro
2016-02-26 21:25                     ` Dmitry Vyukov
2016-02-26 22:07                       ` Al Viro
2016-02-27 22:27                         ` Al Viro
2016-02-28 15:43                           ` Dmitry Vyukov
2016-02-28 16:04                             ` Dmitry Vyukov
2016-02-28 17:01                               ` Al Viro
2016-02-28 20:01                                 ` Al Viro
2016-02-29  9:38                                   ` Dmitry Vyukov
2016-02-29 12:34                                     ` Dmitry Vyukov
2016-02-29 16:11                                       ` Al Viro
2016-02-29 13:09                                   ` Al Viro
2016-02-29 15:54                                     ` Dmitry Vyukov
2016-02-29 16:19                                       ` Al Viro
2016-02-29 18:19                                         ` Dmitry Vyukov
2016-03-01  8:59                                           ` Dmitry Vyukov
2016-02-29 16:45                                     ` Linus Torvalds
2016-02-29 16:50                                       ` Al Viro
2016-02-29 17:20                                         ` Al Viro
2016-02-29 17:24                                         ` Linus Torvalds
2016-02-29 13:43                                   ` David Howells

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