linux-kernel - Re: fs: gpf in simple

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Date:	Mon, 3 Mar 2014 22:40:40 +0100
From:	Jan Kara <jack@...e.cz>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	Al Viro <viro@...IV.linux.org.uk>, linux-fsdevel@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: fs: gpf in simple_setattr

On Sat 01-03-14 15:05:21, Sasha Levin wrote:
> ping again?
> 
> I've been working on it, but don't see an obvious issue.
> 
> It does look like an access to invalid memory easily doable from
> userspace, so it should probably get fixed soon...
  Hum, can you maybe dump the name in dentry passed to simple_setattr()? Or
maybe even the whole path using dentry_path() (but not sure if that will
be workable on half-torn-down fs)? Maybe it will give us a hint at which
filesystem to look...

								Honza

> On 01/08/2014 11:00 AM, Sasha Levin wrote:
> >ping? still happening in -next.
> >
> >On 12/18/2013 07:25 PM, Sasha Levin wrote:
> >>Hi all,
> >>
> >>While fuzzing with trinity inside a KVM tools guest running latest -next kernel, I've stumbled on
> >>the following spew.
> >>
> >>This happens when sb is dereferenced in __mark_inode_dirty():
> >>
> >>                 if (sb->s_op->dirty_inode) <--- HERE
> >>                         sb->s_op->dirty_inode(inode, flags);
> >>
> >>'sb' is pointing to a memory full of poisoned memory (6b6b6b6b6b6b6b6b).
> >>
> >>[  590.469520] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> >>[  590.470737] Dumping ftrace buffer:
> >>[  590.471331]    (ftrace buffer empty)
> >>[  590.471903] Modules linked in:
> >>[  590.472349] CPU: 3 PID: 9685 Comm: trinity-child97 Tainted: G        W
> >>3.13.0-rc4-next-20131218-sasha-00013-g2cebb9b-dirty #4156
> >>[  590.472396] task: ffff8800bc520000 ti: ffff8800bc4fa000 task.ti: ffff8800bc4fa000
> >>[  590.472396] RIP: 0010:[<ffffffff81302d34>]  [<ffffffff81302d34>] __mark_inode_dirty+0xd4/0x360
> >>[  590.475691] RSP: 0018:ffff8800bc4fbda8  EFLAGS: 00010246
> >>[  590.475691] RAX: 6b6b6b6b6b6b6b6b RBX: ffff8802f9002530 RCX: 000000006b6b6b6b
> >>[  590.475691] RDX: 0000000000000000 RSI: 0000000000000007 RDI: ffff8802f9002530
> >>[  590.475691] RBP: ffff8800bc4fbdc8 R08: 0000000000000000 R09: 0000000000000000
> >>[  590.475691] R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000007
> >>[  590.475691] R13: 0000000000000000 R14: ffff8802f8795668 R15: ffff8802f9002530
> >>[  590.475691] FS:  00007f9bba1b7700(0000) GS:ffff8801c8000000(0000) knlGS:0000000000000000
> >>[  590.475691] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> >>[  590.475691] CR2: 00007f9bba17da44 CR3: 00000000bc4e6000 CR4: 00000000000006e0
> >>[  590.475691] Stack:
> >>[  590.475691]  ffff8802f9002530 ffff8800bc4fbe98 0000000000000000 ffff880161244000
> >>[  590.475691]  ffff8800bc4fbdf8 ffffffff8130001b ffff8800bc4fbde8 0000000000001846
> >>[  590.475691]  ffff8800bc4fbe98 0000000000000000 ffff8800bc4fbe78 ffffffff812f3016
> >>[  590.475691] Call Trace:
> >>[  590.475691]  [<ffffffff8130001b>] simple_setattr+0x5b/0x70
> >>[  590.475691]  [<ffffffff812f3016>] notify_change+0x216/0x300
> >>[  590.475691]  [<ffffffff812d0180>] ? zs_malloc+0x1b0/0x200
> >>[  590.475691]  [<ffffffff812d0b15>] chown_common+0x135/0x1c0
> >>[  590.475691]  [<ffffffff812d0c20>] SyS_fchown+0x80/0xd0
> >>[  590.475691]  [<ffffffff843a6d50>] tracesys+0xdd/0xe2
> >>[  590.494436] VFS: Warning: trinity-child15 using old stat() call. Recompile your binary.
> >>[  590.475691] Code: c5 10 48 89 de ff d0 49 8b 45 00 48 85 c0 75 e7 65 ff 0c 25 5c da 00 00 0f 94
> >>c0 84 c0 74 08 e8 b3 33 d7 ff 0f 1f 00 49 8b 46 30 <48> 8b 40 10 48 85 c0 74 08 44 89 e6 48 89 df ff
> >>d0 8b 05 bd 6b
> >>[  590.475691] RIP  [<ffffffff81302d34>] __mark_inode_dirty+0xd4/0x360
> >>[  590.475691]  RSP <ffff8800bc4fbda8>
> >>
> >>
> >>Thanks,
> >>Sasha
> >
> 
> --
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-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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