All of lore.kernel.org
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Network Development <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf
Date: Tue, 7 Nov 2017 08:25:03 -0800	[thread overview]
Message-ID: <CA+55aFwqxZiN_XrZqvbtCsc8W=w895RaB1sjuVP1aTj8JStxzg@mail.gmail.com> (raw)
In-Reply-To: <20171107102156.3fgxt6y6v5y2kqnf@wfg-t540p.sh.intel.com>

On Tue, Nov 7, 2017 at 2:21 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
>
> FYI this happens in v4.14-rc8 -- it's not necessarily a new bug.

Probably not.

Looks like a use-after-free bug in vlan_device_event() judging by the
base pointer:

    ECX: 6b6b6b6b

this is one of those circumstances where having the faddr2line output
for that EIP would make it much easier to see exactly which access it
is that causes problems. There's lots of inlining going on, so without
that it's a pain to figure out.

The code is

   0: 31 c0                xor    %eax,%eax
   2: 8d 76 00              lea    0x0(%esi),%esi
   5: 89 c2                mov    %eax,%edx
   7: 89 c3                mov    %eax,%ebx
   9: 81 e2 ff 0f 00 00    and    $0xfff,%edx
   f: 89 d1                mov    %edx,%ecx
  11: c1 fb 0c              sar    $0xc,%ebx
  14: c1 e9 09              shr    $0x9,%ecx
  17: 8d 0c d9              lea    (%ecx,%ebx,8),%ecx
  1a: 8b 4c 8e 10          mov    0x10(%esi,%ecx,4),%ecx
  1e: 85 c9                test   %ecx,%ecx
  20: 74 34                je     0x56
  22: 81 e2 ff 01 00 00    and    $0x1ff,%edx
  28:* 8b 14 91              mov    (%ecx,%edx,4),%edx <-- trapping instruction
  2b: 85 d2                test   %edx,%edx
  2d: 74 27                je     0x56
  2f: f6 82 30 01 00 00 01 testb  $0x1,0x130(%edx)
  36: 74 1e                je     0x56

and just by going by the constants in question (0xfff and 0x1ff), I
can see that it's one of

    vlan_group_for_each_dev(..) {
        ...
    }

things, but that's pretty much all I can tell.

Apparently we'll get that faddr2line output soon. In the meantime, I
think this is a real bug report but I don't see enough information to
really go on.

Of course, if it's bisectable, that would be great too.

                    Linus

  reply	other threads:[~2017-11-07 16:25 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-07 10:21 [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf Fengguang Wu
2017-11-07 16:25 ` Linus Torvalds [this message]
2017-11-07 16:46   ` Fengguang Wu
2017-11-08  9:48   ` Fengguang Wu
2017-11-08 16:20     ` Linus Torvalds
2017-11-08 16:20       ` [Intel-wired-lan] " Linus Torvalds
2017-11-08 17:12       ` Fengguang Wu
2017-11-08 17:12         ` [Intel-wired-lan] " Fengguang Wu
2017-11-08 17:18         ` Fengguang Wu
2017-11-08 17:18           ` [Intel-wired-lan] " Fengguang Wu
2017-11-08 18:05         ` Linus Torvalds
2017-11-08 18:05           ` [Intel-wired-lan] " Linus Torvalds
2017-11-08 18:36         ` Alexander Duyck
2017-11-08 18:36           ` [Intel-wired-lan] " Alexander Duyck
2017-11-09  3:12           ` Fengguang Wu
2017-11-09  3:12             ` [Intel-wired-lan] " Fengguang Wu
2017-11-09  4:09             ` Fengguang Wu
2017-11-09  4:09               ` [Intel-wired-lan] " Fengguang Wu
2017-11-09  7:22               ` Fengguang Wu
2017-11-09  7:22                 ` [Intel-wired-lan] " Fengguang Wu
2017-11-09  6:34             ` Cong Wang
2017-11-09  6:34               ` [Intel-wired-lan] " Cong Wang
2017-11-09  6:55               ` Fengguang Wu
2017-11-09  6:55                 ` [Intel-wired-lan] " Fengguang Wu
2017-11-09  7:43                 ` Fengguang Wu
2017-11-09  7:43                   ` [Intel-wired-lan] " Fengguang Wu
2017-11-09 15:51               ` Girish Moodalbail
2017-11-09 15:51                 ` [Intel-wired-lan] " Girish Moodalbail
2017-11-10  0:16                 ` Cong Wang
2017-11-10  0:16                   ` [Intel-wired-lan] " Cong Wang
2017-11-12 19:31         ` Linus Torvalds
2017-11-12 19:31           ` [Intel-wired-lan] " Linus Torvalds
2017-11-13  1:13           ` CONFIG_DEBUG_INFO_SPLIT impacts on faddr2line Fengguang Wu
2017-11-13  1:13             ` [Intel-wired-lan] " Fengguang Wu
2017-11-13  2:05             ` Zhang Rui
2017-11-13  2:05               ` [Intel-wired-lan] " Zhang Rui
2017-11-13  2:22               ` Fengguang Wu
2017-11-13  2:22                 ` [Intel-wired-lan] " Fengguang Wu
2017-11-13 18:52             ` Andi Kleen
2017-11-13 18:52               ` [Intel-wired-lan] " Andi Kleen
2017-11-13 19:14               ` Linus Torvalds
2017-11-13 19:14                 ` [Intel-wired-lan] " Linus Torvalds
2017-11-13 20:10                 ` Andi Kleen
2017-11-13 20:10                   ` [Intel-wired-lan] " Andi Kleen
2017-11-13 20:14                   ` H.J. Lu
2017-11-13 20:14                     ` [Intel-wired-lan] " H.J. Lu
2017-11-13 20:56                   ` Linus Torvalds
2017-11-13 20:56                     ` [Intel-wired-lan] " Linus Torvalds
2017-11-13 21:41                     ` Andi Kleen
2017-11-13 21:41                       ` [Intel-wired-lan] " Andi Kleen
2017-11-13 21:57                       ` Linus Torvalds
2017-11-13 21:57                         ` [Intel-wired-lan] " Linus Torvalds
2017-11-13 23:51                         ` Andi Kleen
2017-11-13 23:51                           ` [Intel-wired-lan] " Andi Kleen
2017-11-14  8:13               ` Fengguang Wu
2017-11-14  8:13                 ` [Intel-wired-lan] " Fengguang Wu
2017-11-09  2:43     ` [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf Fengguang Wu
2017-11-09  6:48       ` Fengguang Wu

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='CA+55aFwqxZiN_XrZqvbtCsc8W=w895RaB1sjuVP1aTj8JStxzg@mail.gmail.com' \
    --to=torvalds@linux-foundation.org \
    --cc=davem@davemloft.net \
    --cc=fengguang.wu@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    /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.