WARNING: kobject bug in br_add_if

WARNING: kobject bug in br_add_if

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
10b84daddbec72c6b440216a69de9a9605127f7a (Sat Mar 31 17:59:00 2018 +0000)
Merge branch 'perf-urgent-for-linus' of  
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=de73361ee4971b6e6f75

So far this crash happened 4 times on net-next, upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5007286875455488
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-2760467897697295172
compiler: gcc (GCC) 7.1.1 20170620

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006
------------[ cut here ]------------
binder: 23650:23651 unknown command 1078223622
kobject_add_internal failed for brport (error: -12 parent: bond0)
binder: 23650:23651 ioctl c0306201 2000dfd0 returned -22
WARNING: CPU: 1 PID: 23647 at lib/kobject.c:242  
kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 23647 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #374
binder: BINDER_SET_CONTEXT_MGR already set
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x24d lib/dump_stack.c:53
  panic+0x1e4/0x41c kernel/panic.c:183
  __warn+0x1dc/0x200 kernel/panic.c:547
  report_bug+0x1f4/0x2b0 lib/bug.c:186
  fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
  fixup_bug arch/x86/kernel/traps.c:247 [inline]
  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
  invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
RIP: 0010:kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
RSP: 0018:ffff8801d089f560 EFLAGS: 00010286
RAX: dffffc0000000008 RBX: ffff8801adbee178 RCX: ffffffff815b193e
RDX: 0000000000040000 RSI: ffffc900022aa000 RDI: 1ffff1003a113e31
RBP: ffff8801d089f658 R08: 1ffff1003a113df3 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a113eb2
R13: 00000000fffffff4 R14: ffff8801abd88828 R15: ffff8801d75a1e00
  kobject_add_varg lib/kobject.c:364 [inline]
  kobject_init_and_add+0xf9/0x150 lib/kobject.c:436
  br_add_if+0x79a/0x1a70 net/bridge/br_if.c:533
  add_del_if+0xf4/0x140 net/bridge/br_ioctl.c:101
  br_dev_ioctl+0xa2/0xc0 net/bridge/br_ioctl.c:396
  dev_ifsioc+0x333/0x9b0 net/core/dev_ioctl.c:334
  dev_ioctl+0x176/0xbe0 net/core/dev_ioctl.c:500
  sock_do_ioctl+0x1ba/0x390 net/socket.c:981
  sock_ioctl+0x367/0x670 net/socket.c:1081
  vfs_ioctl fs/ioctl.c:46 [inline]
  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
  SYSC_ioctl fs/ioctl.c:701 [inline]
  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454e79
RSP: 002b:00007eff7dab7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007eff7dab86d4 RCX: 0000000000454e79
RDX: 0000000020000000 RSI: 00000000000089a2 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015
R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@googlegroups.com.

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is  
merged
into any tree, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
report.
Note: all commands must start from beginning of the line in the email body.

Re: WARNING: kobject bug in br_add_if

[Dmitry Vyukov]

On Wed, Apr 11, 2018 at 5:15 PM, syzbot
<syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot hit the following crash on upstream commit
> 10b84daddbec72c6b440216a69de9a9605127f7a (Sat Mar 31 17:59:00 2018 +0000)
> Merge branch 'perf-urgent-for-linus' of
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=de73361ee4971b6e6f75
>
> So far this crash happened 4 times on net-next, upstream.
> Unfortunately, I don't have any reproducer for this crash yet.
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=5007286875455488
> Kernel config:
> https://syzkaller.appspot.com/x/.config?id=-2760467897697295172
> compiler: gcc (GCC) 7.1.1 20170620
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.

+Greg

The plan is to remove this WARNING from kobject_add, if there are no objections.

> ------------[ cut here ]------------
> binder: 23650:23651 unknown command 1078223622
> kobject_add_internal failed for brport (error: -12 parent: bond0)
> binder: 23650:23651 ioctl c0306201 2000dfd0 returned -22
> WARNING: CPU: 1 PID: 23647 at lib/kobject.c:242
> kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
> Kernel panic - not syncing: panic_on_warn set ...
>
> CPU: 1 PID: 23647 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #374
> binder: BINDER_SET_CONTEXT_MGR already set
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x24d lib/dump_stack.c:53
>  panic+0x1e4/0x41c kernel/panic.c:183
>  __warn+0x1dc/0x200 kernel/panic.c:547
>  report_bug+0x1f4/0x2b0 lib/bug.c:186
>  fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
>  fixup_bug arch/x86/kernel/traps.c:247 [inline]
>  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
>  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
>  invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
> RIP: 0010:kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
> RSP: 0018:ffff8801d089f560 EFLAGS: 00010286
> RAX: dffffc0000000008 RBX: ffff8801adbee178 RCX: ffffffff815b193e
> RDX: 0000000000040000 RSI: ffffc900022aa000 RDI: 1ffff1003a113e31
> RBP: ffff8801d089f658 R08: 1ffff1003a113df3 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a113eb2
> R13: 00000000fffffff4 R14: ffff8801abd88828 R15: ffff8801d75a1e00
>  kobject_add_varg lib/kobject.c:364 [inline]
>  kobject_init_and_add+0xf9/0x150 lib/kobject.c:436
>  br_add_if+0x79a/0x1a70 net/bridge/br_if.c:533
>  add_del_if+0xf4/0x140 net/bridge/br_ioctl.c:101
>  br_dev_ioctl+0xa2/0xc0 net/bridge/br_ioctl.c:396
>  dev_ifsioc+0x333/0x9b0 net/core/dev_ioctl.c:334
>  dev_ioctl+0x176/0xbe0 net/core/dev_ioctl.c:500
>  sock_do_ioctl+0x1ba/0x390 net/socket.c:981
>  sock_ioctl+0x367/0x670 net/socket.c:1081
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>  SYSC_ioctl fs/ioctl.c:701 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>  entry_SYSCALL_64_after_hwframe+0x42/0xb7
> RIP: 0033:0x454e79
> RSP: 002b:00007eff7dab7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007eff7dab86d4 RCX: 0000000000454e79
> RDX: 0000000020000000 RSI: 00000000000089a2 RDI: 0000000000000014
> RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015
> R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report.
> If you forgot to add the Reported-by tag, once the fix for this bug is
> merged
> into any tree, please reply to this email with:
> #syz fix: exact-commit-title
> To mark this as a duplicate of another syzbot report, please reply with:
> #syz dup: exact-subject-of-another-report
> If it's a one-off invalid bug report, please reply with:
> #syz invalid
> Note: if the crash happens again, it will cause creation of a new bug
> report.
> Note: all commands must start from beginning of the line in the email body.
>
> --
> You received this message because you are subscribed to the Google Groups
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> For more options, visit https://groups.google.com/d/optout.

Re: WARNING: kobject bug in br_add_if

[Hangbin Liu]

On Wed, Apr 11, 2018 at 05:18:23PM +0200, Dmitry Vyukov wrote:
> On Wed, Apr 11, 2018 at 5:15 PM, syzbot
> <syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com> wrote:
> > Hello,
> >
> > syzbot hit the following crash on upstream commit
> > 10b84daddbec72c6b440216a69de9a9605127f7a (Sat Mar 31 17:59:00 2018 +0000)
> > Merge branch 'perf-urgent-for-linus' of
> > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
> > syzbot dashboard link:
> > https://syzkaller.appspot.com/bug?extid=de73361ee4971b6e6f75
> >
> > So far this crash happened 4 times on net-next, upstream.
> > Unfortunately, I don't have any reproducer for this crash yet.
> > Raw console output:
> > https://syzkaller.appspot.com/x/log.txt?id=5007286875455488
> > Kernel config:
> > https://syzkaller.appspot.com/x/.config?id=-2760467897697295172
> > compiler: gcc (GCC) 7.1.1 20170620
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
> > It will help syzbot understand when the bug is fixed. See footer for
> > details.
> > If you forward the report, please keep this part and the footer.
> 
> +Greg
> 
> The plan is to remove this WARNING from kobject_add, if there are no objections.

Hi Dmitry,

For this bug, why should we remove the WARNING instead of adding a check in
br_add_if()? Something like

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 82c1a6f..79dcc3d 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -518,8 +518,8 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
                return -ELOOP;
        }

-       /* Device is already being bridged */
-       if (br_port_exists(dev))
+       /* Device still has master upper dev */
+       if (netdev_master_upper_dev_get(dev))
                return -EBUSY;

        /* No bridging devices that dislike that (e.g. wireless) */

Thanks
Hangbin
> 
> > ------------[ cut here ]------------
> > binder: 23650:23651 unknown command 1078223622
> > kobject_add_internal failed for brport (error: -12 parent: bond0)
> > binder: 23650:23651 ioctl c0306201 2000dfd0 returned -22
> > WARNING: CPU: 1 PID: 23647 at lib/kobject.c:242
> > kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
> > Kernel panic - not syncing: panic_on_warn set ...
> >
> > CPU: 1 PID: 23647 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #374
> > binder: BINDER_SET_CONTEXT_MGR already set
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Call Trace:
> >  __dump_stack lib/dump_stack.c:17 [inline]
> >  dump_stack+0x194/0x24d lib/dump_stack.c:53
> >  panic+0x1e4/0x41c kernel/panic.c:183
> >  __warn+0x1dc/0x200 kernel/panic.c:547
> >  report_bug+0x1f4/0x2b0 lib/bug.c:186
> >  fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
> >  fixup_bug arch/x86/kernel/traps.c:247 [inline]
> >  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
> >  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
> >  invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
> > RIP: 0010:kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
> > RSP: 0018:ffff8801d089f560 EFLAGS: 00010286
> > RAX: dffffc0000000008 RBX: ffff8801adbee178 RCX: ffffffff815b193e
> > RDX: 0000000000040000 RSI: ffffc900022aa000 RDI: 1ffff1003a113e31
> > RBP: ffff8801d089f658 R08: 1ffff1003a113df3 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a113eb2
> > R13: 00000000fffffff4 R14: ffff8801abd88828 R15: ffff8801d75a1e00
> >  kobject_add_varg lib/kobject.c:364 [inline]
> >  kobject_init_and_add+0xf9/0x150 lib/kobject.c:436
> >  br_add_if+0x79a/0x1a70 net/bridge/br_if.c:533
> >  add_del_if+0xf4/0x140 net/bridge/br_ioctl.c:101
> >  br_dev_ioctl+0xa2/0xc0 net/bridge/br_ioctl.c:396
> >  dev_ifsioc+0x333/0x9b0 net/core/dev_ioctl.c:334
> >  dev_ioctl+0x176/0xbe0 net/core/dev_ioctl.c:500
> >  sock_do_ioctl+0x1ba/0x390 net/socket.c:981
> >  sock_ioctl+0x367/0x670 net/socket.c:1081
> >  vfs_ioctl fs/ioctl.c:46 [inline]
> >  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
> >  SYSC_ioctl fs/ioctl.c:701 [inline]
> >  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
> >  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
> >  entry_SYSCALL_64_after_hwframe+0x42/0xb7
> > RIP: 0033:0x454e79
> > RSP: 002b:00007eff7dab7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> > RAX: ffffffffffffffda RBX: 00007eff7dab86d4 RCX: 0000000000454e79
> > RDX: 0000000020000000 RSI: 00000000000089a2 RDI: 0000000000000014
> > RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015
> > R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006
> > Dumping ftrace buffer:
> >    (ftrace buffer empty)
> > Kernel Offset: disabled
> > Rebooting in 86400 seconds..

Re: WARNING: kobject bug in br_add_if

[Dmitry Vyukov]

On Thu, Apr 26, 2018 at 8:13 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
> On Wed, Apr 11, 2018 at 05:18:23PM +0200, Dmitry Vyukov wrote:
>> On Wed, Apr 11, 2018 at 5:15 PM, syzbot
>> <syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com> wrote:
>> > Hello,
>> >
>> > syzbot hit the following crash on upstream commit
>> > 10b84daddbec72c6b440216a69de9a9605127f7a (Sat Mar 31 17:59:00 2018 +0000)
>> > Merge branch 'perf-urgent-for-linus' of
>> > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
>> > syzbot dashboard link:
>> > https://syzkaller.appspot.com/bug?extid=de73361ee4971b6e6f75
>> >
>> > So far this crash happened 4 times on net-next, upstream.
>> > Unfortunately, I don't have any reproducer for this crash yet.
>> > Raw console output:
>> > https://syzkaller.appspot.com/x/log.txt?id=5007286875455488
>> > Kernel config:
>> > https://syzkaller.appspot.com/x/.config?id=-2760467897697295172
>> > compiler: gcc (GCC) 7.1.1 20170620
>> >
>> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> > Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
>> > It will help syzbot understand when the bug is fixed. See footer for
>> > details.
>> > If you forward the report, please keep this part and the footer.
>>
>> +Greg
>>
>> The plan is to remove this WARNING from kobject_add, if there are no objections.
>
> Hi Dmitry,
>
> For this bug, why should we remove the WARNING instead of adding a check in
> br_add_if()? Something like


Mainline because nobody wants to fix these.
If you think this is a real bug and you are ready to fix it, please
mail an official patch.


> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index 82c1a6f..79dcc3d 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -518,8 +518,8 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
>                 return -ELOOP;
>         }
>
> -       /* Device is already being bridged */
> -       if (br_port_exists(dev))
> +       /* Device still has master upper dev */
> +       if (netdev_master_upper_dev_get(dev))
>                 return -EBUSY;
>
>         /* No bridging devices that dislike that (e.g. wireless) */
>
> Thanks
> Hangbin
>>
>> > ------------[ cut here ]------------
>> > binder: 23650:23651 unknown command 1078223622
>> > kobject_add_internal failed for brport (error: -12 parent: bond0)
>> > binder: 23650:23651 ioctl c0306201 2000dfd0 returned -22
>> > WARNING: CPU: 1 PID: 23647 at lib/kobject.c:242
>> > kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
>> > Kernel panic - not syncing: panic_on_warn set ...
>> >
>> > CPU: 1 PID: 23647 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #374
>> > binder: BINDER_SET_CONTEXT_MGR already set
>> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> > Google 01/01/2011
>> > Call Trace:
>> >  __dump_stack lib/dump_stack.c:17 [inline]
>> >  dump_stack+0x194/0x24d lib/dump_stack.c:53
>> >  panic+0x1e4/0x41c kernel/panic.c:183
>> >  __warn+0x1dc/0x200 kernel/panic.c:547
>> >  report_bug+0x1f4/0x2b0 lib/bug.c:186
>> >  fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
>> >  fixup_bug arch/x86/kernel/traps.c:247 [inline]
>> >  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
>> >  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
>> >  invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
>> > RIP: 0010:kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
>> > RSP: 0018:ffff8801d089f560 EFLAGS: 00010286
>> > RAX: dffffc0000000008 RBX: ffff8801adbee178 RCX: ffffffff815b193e
>> > RDX: 0000000000040000 RSI: ffffc900022aa000 RDI: 1ffff1003a113e31
>> > RBP: ffff8801d089f658 R08: 1ffff1003a113df3 R09: 0000000000000000
>> > R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a113eb2
>> > R13: 00000000fffffff4 R14: ffff8801abd88828 R15: ffff8801d75a1e00
>> >  kobject_add_varg lib/kobject.c:364 [inline]
>> >  kobject_init_and_add+0xf9/0x150 lib/kobject.c:436
>> >  br_add_if+0x79a/0x1a70 net/bridge/br_if.c:533
>> >  add_del_if+0xf4/0x140 net/bridge/br_ioctl.c:101
>> >  br_dev_ioctl+0xa2/0xc0 net/bridge/br_ioctl.c:396
>> >  dev_ifsioc+0x333/0x9b0 net/core/dev_ioctl.c:334
>> >  dev_ioctl+0x176/0xbe0 net/core/dev_ioctl.c:500
>> >  sock_do_ioctl+0x1ba/0x390 net/socket.c:981
>> >  sock_ioctl+0x367/0x670 net/socket.c:1081
>> >  vfs_ioctl fs/ioctl.c:46 [inline]
>> >  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>> >  SYSC_ioctl fs/ioctl.c:701 [inline]
>> >  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>> >  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>> >  entry_SYSCALL_64_after_hwframe+0x42/0xb7
>> > RIP: 0033:0x454e79
>> > RSP: 002b:00007eff7dab7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>> > RAX: ffffffffffffffda RBX: 00007eff7dab86d4 RCX: 0000000000454e79
>> > RDX: 0000000020000000 RSI: 00000000000089a2 RDI: 0000000000000014
>> > RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
>> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015
>> > R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006
>> > Dumping ftrace buffer:
>> >    (ftrace buffer empty)
>> > Kernel Offset: disabled
>> > Rebooting in 86400 seconds..

Re: WARNING: kobject bug in br_add_if

[Hangbin Liu]

On Thu, Apr 26, 2018 at 10:04:16AM +0200, Dmitry Vyukov wrote:
> On Thu, Apr 26, 2018 at 8:13 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
> > On Wed, Apr 11, 2018 at 05:18:23PM +0200, Dmitry Vyukov wrote:
> >> On Wed, Apr 11, 2018 at 5:15 PM, syzbot
> >> <syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com> wrote:
> >> > Hello,
> >> >
> >> > syzbot hit the following crash on upstream commit
> >> > 10b84daddbec72c6b440216a69de9a9605127f7a (Sat Mar 31 17:59:00 2018 +0000)
> >> > Merge branch 'perf-urgent-for-linus' of
> >> > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
> >> > syzbot dashboard link:
> >> > https://syzkaller.appspot.com/bug?extid=de73361ee4971b6e6f75
> >> >
> >> > So far this crash happened 4 times on net-next, upstream.
> >> > Unfortunately, I don't have any reproducer for this crash yet.
> >> > Raw console output:
> >> > https://syzkaller.appspot.com/x/log.txt?id=5007286875455488
> >> > Kernel config:
> >> > https://syzkaller.appspot.com/x/.config?id=-2760467897697295172
> >> > compiler: gcc (GCC) 7.1.1 20170620
> >> >
> >> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >> > Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com
> >> > It will help syzbot understand when the bug is fixed. See footer for
> >> > details.
> >> > If you forward the report, please keep this part and the footer.
> >>
> >> +Greg
> >>
> >> The plan is to remove this WARNING from kobject_add, if there are no objections.
> >
> > Hi Dmitry,
> >
> > For this bug, why should we remove the WARNING instead of adding a check in
> > br_add_if()? Something like
> 
> 
> Mainline because nobody wants to fix these.
> If you think this is a real bug and you are ready to fix it, please
> mail an official patch.
> 
> >> > ------------[ cut here ]------------
> >> > binder: 23650:23651 unknown command 1078223622
> >> > kobject_add_internal failed for brport (error: -12 parent: bond0)

Re-checked the error. This is a -ENOMEM. So normally we could ignore it.

But on the other hand, although we could find out the slave iface's
master in netdev_master_upper_dev_link(). It already go much further
and allocate some resource and change iface state. e.g.

[54273.968516] br0: port 1(em1) entered blocking state
[54273.973979] br0: port 1(em1) entered disabled state

So I think we'd better return as early as possible. I will post a fix
for this.

Thanks
Hangbin

> >> > binder: 23650:23651 ioctl c0306201 2000dfd0 returned -22
> >> > WARNING: CPU: 1 PID: 23647 at lib/kobject.c:242
> >> > kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
> >> > Kernel panic - not syncing: panic_on_warn set ...
> >> >
> >> > CPU: 1 PID: 23647 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #374
> >> > binder: BINDER_SET_CONTEXT_MGR already set
> >> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> >> > Google 01/01/2011
> >> > Call Trace:
> >> >  __dump_stack lib/dump_stack.c:17 [inline]
> >> >  dump_stack+0x194/0x24d lib/dump_stack.c:53
> >> >  panic+0x1e4/0x41c kernel/panic.c:183
> >> >  __warn+0x1dc/0x200 kernel/panic.c:547
> >> >  report_bug+0x1f4/0x2b0 lib/bug.c:186
> >> >  fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
> >> >  fixup_bug arch/x86/kernel/traps.c:247 [inline]
> >> >  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
> >> >  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
> >> >  invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
> >> > RIP: 0010:kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240
> >> > RSP: 0018:ffff8801d089f560 EFLAGS: 00010286
> >> > RAX: dffffc0000000008 RBX: ffff8801adbee178 RCX: ffffffff815b193e
> >> > RDX: 0000000000040000 RSI: ffffc900022aa000 RDI: 1ffff1003a113e31
> >> > RBP: ffff8801d089f658 R08: 1ffff1003a113df3 R09: 0000000000000000
> >> > R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a113eb2
> >> > R13: 00000000fffffff4 R14: ffff8801abd88828 R15: ffff8801d75a1e00
> >> >  kobject_add_varg lib/kobject.c:364 [inline]
> >> >  kobject_init_and_add+0xf9/0x150 lib/kobject.c:436
> >> >  br_add_if+0x79a/0x1a70 net/bridge/br_if.c:533
> >> >  add_del_if+0xf4/0x140 net/bridge/br_ioctl.c:101
> >> >  br_dev_ioctl+0xa2/0xc0 net/bridge/br_ioctl.c:396
> >> >  dev_ifsioc+0x333/0x9b0 net/core/dev_ioctl.c:334
> >> >  dev_ioctl+0x176/0xbe0 net/core/dev_ioctl.c:500
> >> >  sock_do_ioctl+0x1ba/0x390 net/socket.c:981
> >> >  sock_ioctl+0x367/0x670 net/socket.c:1081
> >> >  vfs_ioctl fs/ioctl.c:46 [inline]
> >> >  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
> >> >  SYSC_ioctl fs/ioctl.c:701 [inline]
> >> >  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
> >> >  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
> >> >  entry_SYSCALL_64_after_hwframe+0x42/0xb7
> >> > RIP: 0033:0x454e79
> >> > RSP: 002b:00007eff7dab7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> >> > RAX: ffffffffffffffda RBX: 00007eff7dab86d4 RCX: 0000000000454e79
> >> > RDX: 0000000020000000 RSI: 00000000000089a2 RDI: 0000000000000014
> >> > RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
> >> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015
> >> > R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006
> >> > Dumping ftrace buffer:
> >> >    (ftrace buffer empty)
> >> > Kernel Offset: disabled
> >> > Rebooting in 86400 seconds..

Re: WARNING: kobject bug in br_add_if

[Nikolay Aleksandrov]

On 26/04/18 13:37, Hangbin Liu wrote:
> On Thu, Apr 26, 2018 at 10:04:16AM +0200, Dmitry Vyukov wrote:
>> On Thu, Apr 26, 2018 at 8:13 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
>>> On Wed, Apr 11, 2018 at 05:18:23PM +0200, Dmitry Vyukov wrote:
>>>> On Wed, Apr 11, 2018 at 5:15 PM, syzbot
>>>> <syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com> wrote:
>>>>> kobject_add_internal failed for brport (error: -12 parent: bond0)
[snip]
> 
> Re-checked the error. This is a -ENOMEM. So normally we could ignore it.
> 
> But on the other hand, although we could find out the slave iface's
> master in netdev_master_upper_dev_link(). It already go much further
> and allocate some resource and change iface state. e.g.
> 
> [54273.968516] br0: port 1(em1) entered blocking state
> [54273.973979] br0: port 1(em1) entered disabled state
> 
> So I think we'd better return as early as possible. I will post a fix
> for this.
> 
> Thanks
> Hangbin

If I'm not mistaken the bridge allocated resources for the port are
cleaned on kobject_init_and_add() error return. Or are you talking
about some other resources ?

Re: WARNING: kobject bug in br_add_if

[Nikolay Aleksandrov]

On 26/04/18 14:49, Nikolay Aleksandrov wrote:
> On 26/04/18 13:37, Hangbin Liu wrote:
>> On Thu, Apr 26, 2018 at 10:04:16AM +0200, Dmitry Vyukov wrote:
>>> On Thu, Apr 26, 2018 at 8:13 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
>>>> On Wed, Apr 11, 2018 at 05:18:23PM +0200, Dmitry Vyukov wrote:
>>>>> On Wed, Apr 11, 2018 at 5:15 PM, syzbot
>>>>> <syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com> wrote:
>>>>>> kobject_add_internal failed for brport (error: -12 parent: bond0)
> [snip]
>>
>> Re-checked the error. This is a -ENOMEM. So normally we could ignore it.
>>
>> But on the other hand, although we could find out the slave iface's
>> master in netdev_master_upper_dev_link(). It already go much further
>> and allocate some resource and change iface state. e.g.
>>
>> [54273.968516] br0: port 1(em1) entered blocking state
>> [54273.973979] br0: port 1(em1) entered disabled state
>>
>> So I think we'd better return as early as possible. I will post a fix
>> for this.
>>
>> Thanks
>> Hangbin
> 
> If I'm not mistaken the bridge allocated resources for the port are
> cleaned on kobject_init_and_add() error return. Or are you talking
> about some other resources ?
> 

Ah, my bad - you weren't talking about resource freeing.
Nevermind my comment.