From: Sasha Levin <sasha.levin@oracle.com>
To: David Rientjes <rientjes@google.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
Dave Jones <davej@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: fs: use after free in /proc/pid/mountinfo
Date: Fri, 04 Jul 2014 10:55:13 -0400 [thread overview]
Message-ID: <53B6C051.2060704@oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1407031434470.10658@chino.kir.corp.google.com>
On 07/03/2014 05:37 PM, David Rientjes wrote:
> On Wed, 2 Jul 2014, Sasha Levin wrote:
>
>>> Hi all,
>>>
>>> While fuzzing with trinity inside a KVM tools guest running the latest -next
>>> kernel I've stumbled on the following spew:
>>>
>>> [ 3569.869749] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
>>> [ 3569.869769] Dumping ftrace buffer:
>>> [ 3569.869879] (ftrace buffer empty)
>>> [ 3569.869894] Modules linked in:
>>> [ 3569.869900] CPU: 7 PID: 10239 Comm: trinity-c86 Tainted: G W 3.16.0-rc3-next-20140701-sasha-00023-g4eb2544-dirty #759
>>> [ 3569.869906] task: ffff88039e873000 ti: ffff880393f8c000 task.ti: ffff880393f8c000
>>> [ 3569.869932] RIP: show_mountinfo (fs/proc_namespace.c:127)
>>> [ 3569.869938] RSP: 0018:ffff880393f8fd08 EFLAGS: 00010282
>>> [ 3569.869943] RAX: ffff880200c6d208 RBX: 6b6b6b6b6b6b6b03 RCX: 0000000000000074
>>> [ 3569.869946] RDX: 0000000000000000 RSI: 6b6b6b6b6b6b6b03 RDI: ffff880200c6d208
>>> [ 3569.869953] RBP: ffff880393f8fd58 R08: 0000000000000001 R09: ffff88039e873d38
>>> [ 3569.869957] R10: 0000000000000001 R11: 0000000000000000 R12: ffff880200c6d208
>>> [ 3569.869962] R13: 6b6b6b6b6b6b6b6b R14: ffff880393f8ff50 R15: ffff880200c6d208
>>> [ 3569.869966] FS: 00007f6f20db9700(0000) GS:ffff8801ece00000(0000) knlGS:0000000000000000
>>> [ 3569.869969] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [ 3569.869974] CR2: 00007f6f20bee000 CR3: 00000003a0775000 CR4: 00000000000006a0
>>> [ 3569.869992] Stack:
>>> [ 3569.870011] ffff880393f8ff50 ffff880200c6d208 ffff880393f8fd48 ffffffff984e10ea
>>> [ 3569.870025] ffffffff9532c7fe ffff8802069a3b80 0000000000000065 6b6b6b6b6b6b6b6b
>>> [ 3569.870036] ffff880393f8ff50 ffff880200c6d208 ffff880393f8fd68 ffffffff9532c756
>>> [ 3569.870038] Call Trace:
>>> [ 3569.870051] ? down_read (kernel/locking/rwsem.c:45 (discriminator 2))
>>> [ 3569.870059] ? m_start (kernel/module.c:3634)
>>> [ 3569.870069] m_show (kernel/module.c:3649)
>>> [ 3569.870076] seq_read (fs/seq_file.c:235)
>>> [ 3569.870081] ? single_open_size (fs/seq_file.c:166)
>>> [ 3569.870092] do_loop_readv_writev (fs/read_write.c:708)
>>> [ 3569.870098] ? single_open_size (fs/seq_file.c:166)
>>> [ 3569.870098] do_readv_writev (fs/read_write.c:840)
>>> [ 3569.870098] ? get_parent_ip (kernel/sched/core.c:2550)
>>> [ 3569.870098] ? mutex_lock_nested (./arch/x86/include/asm/preempt.h:98 kernel/locking/mutex.c:570 kernel/locking/mutex.c:587)
>>> [ 3569.870098] ? __fdget_pos (fs/file.c:714)
>>> [ 3569.870098] ? __fdget_pos (fs/file.c:714)
>>> [ 3569.870098] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2557 kernel/locking/lockdep.c:2599)
>>> [ 3569.870098] ? __fget_light (fs/file.c:685)
>>> [ 3569.870098] vfs_readv (fs/read_write.c:866)
>>> [ 3569.870098] SyS_readv (fs/read_write.c:892 fs/read_write.c:884)
>>> [ 3569.870098] tracesys (arch/x86/kernel/entry_64.S:542)
>>> [ 3569.870098] Code: 00 00 00 00 66 66 66 66 90 55 48 89 e5 48 83 ec 50 48 89 5d d8 48 89 f3 4c 89 65 e0 49 89 fc 4c 89 6d e8 4c 89 75 f0 4c 89 7d f8 <48> 8b 06 48 89 75 b0 4c 8b 76 08 8b 96 ec 00 00 00 48 89 45 b8
>>> All code
>>> ========
>>> 0: 00 00 add %al,(%rax)
>>> 2: 00 00 add %al,(%rax)
>>> 4: 66 66 66 66 90 data32 data32 data32 xchg %ax,%ax
>>> 9: 55 push %rbp
>>> a: 48 89 e5 mov %rsp,%rbp
>>> d: 48 83 ec 50 sub $0x50,%rsp
>>> 11: 48 89 5d d8 mov %rbx,-0x28(%rbp)
>>> 15: 48 89 f3 mov %rsi,%rbx
>>> 18: 4c 89 65 e0 mov %r12,-0x20(%rbp)
>>> 1c: 49 89 fc mov %rdi,%r12
>>> 1f: 4c 89 6d e8 mov %r13,-0x18(%rbp)
>>> 23: 4c 89 75 f0 mov %r14,-0x10(%rbp)
>>> 27: 4c 89 7d f8 mov %r15,-0x8(%rbp)
>>> 2b:* 48 8b 06 mov (%rsi),%rax <-- trapping instruction
>>> 2e: 48 89 75 b0 mov %rsi,-0x50(%rbp)
>>> 32: 4c 8b 76 08 mov 0x8(%rsi),%r14
>>> 36: 8b 96 ec 00 00 00 mov 0xec(%rsi),%edx
>>> 3c: 48 89 45 b8 mov %rax,-0x48(%rbp)
>
> Does this now reproduce on Linus's tree? If so, does reverting commit
> 058504edd026 ("fs/seq_file: fallback to vmalloc allocation") prevent this
> issue?
>
> This is a use-after-free since the poison value is 0x6b and I'm presuming
> that your /proc/self/mountinfo may be larger than PAGE_SIZE in your
> testing environment.
>
Good call, reverting that patch made both issues go away.
Thanks,
Sasha
next prev parent reply other threads:[~2014-07-04 14:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-02 11:55 fs: use after free in /proc/pid/mountinfo Sasha Levin
2014-07-03 3:15 ` Sasha Levin
2014-07-03 21:37 ` David Rientjes
2014-07-04 14:55 ` Sasha Levin [this message]
2014-07-04 22:35 ` [stable] please do not merge 058504edd026 (was Re: fs: use after free in /proc/pid/mountinfo) David Rientjes
2014-07-04 22:35 ` David Rientjes
2014-07-07 23:05 ` [stable] " Greg KH
2014-07-07 23:05 ` Greg KH
2014-07-07 23:06 ` [stable] " Andrew Morton
2014-07-07 23:19 ` Greg KH
2014-07-07 23:19 ` Greg KH
2014-07-06 10:04 ` fs: use after free in /proc/pid/mountinfo Heiko Carstens
2014-07-09 14:24 ` Heiko Carstens
2014-07-09 20:31 ` Andrew Morton
2014-07-09 22:10 ` Sasha Levin
2014-07-09 22:59 ` Andrew Morton
2014-07-15 13:52 ` Sasha Levin
2014-07-15 23:01 ` David Rientjes
2014-07-23 20:57 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=53B6C051.2060704@oracle.com \
--to=sasha.levin@oracle.com \
--cc=davej@redhat.com \
--cc=heiko.carstens@de.ibm.com \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rientjes@google.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.