WARNING in geneve_exit_batch_net (2)

WARNING in geneve_exit_batch_net (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    f8788d86 Linux 5.6-rc3
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=138dd22de00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5d2e033af114153f
dashboard link: https://syzkaller.appspot.com/bug?extid=68a8ed58e3d17c700de5
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16601d31e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14fdf8f9e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+68a8ed58e3d17c700de5@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 304 at drivers/net/geneve.c:1849 geneve_destroy_tunnels drivers/net/geneve.c:1849 [inline]
WARNING: CPU: 0 PID: 304 at drivers/net/geneve.c:1849 geneve_exit_batch_net+0x2b1/0x300 drivers/net/geneve.c:1859
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 304 Comm: kworker/u4:4 Not tainted 5.6.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fb/0x318 lib/dump_stack.c:118
 panic+0x264/0x7a9 kernel/panic.c:221
 __warn+0x209/0x210 kernel/panic.c:582
 report_bug+0x1b6/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0xcf/0x1c0 arch/x86/kernel/traps.c:267
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:geneve_destroy_tunnels drivers/net/geneve.c:1849 [inline]
RIP: 0010:geneve_exit_batch_net+0x2b1/0x300 drivers/net/geneve.c:1859
Code: 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 46 aa d1 fc 48 8b 1b 4c 39 fb 74 13 e8 c9 80 94 fc e9 f4 fd ff ff e8 bf 80 94 fc <0f> 0b eb cf e8 b6 80 94 fc eb 05 e8 af 80 94 fc 48 8d 7d c0 e8 c6
RSP: 0018:ffffc90001917c08 EFLAGS: 00010293
RAX: ffffffff84e288c1 RBX: ffff8880a7bc6120 RCX: ffff8880a88304c0
RDX: 0000000000000000 RSI: ffffc90001917c28 RDI: ffff8880a47da068
RBP: ffffc90001917c68 R08: ffffffff866be459 R09: fffffbfff12b21a9
R10: fffffbfff12b21a9 R11: 0000000000000000 R12: ffffc90001917c28
R13: dffffc0000000000 R14: ffff8880a1ca0dd0 R15: ffffc90001917c98
 ops_exit_list net/core/net_namespace.c:175 [inline]
 cleanup_net+0x78b/0xb80 net/core/net_namespace.c:589
 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264
 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Re: WARNING in geneve_exit_batch_net (2)

[syzbot]

syzbot has bisected this bug to:

commit 4e645b47c4f000a503b9c90163ad905786b9bc1d
Author: Florian Westphal <fw@strlen.de>
Date:   Thu Nov 30 23:21:02 2017 +0000

    netfilter: core: make nf_unregister_net_hooks simple wrapper again

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1594fbfde00000
start commit:   63623fd4 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1794fbfde00000
console output: https://syzkaller.appspot.com/x/log.txt?x=1394fbfde00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9833e26bab355358
dashboard link: https://syzkaller.appspot.com/bug?extid=68a8ed58e3d17c700de5
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14f08165e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17902329e00000

Reported-by: syzbot+68a8ed58e3d17c700de5@syzkaller.appspotmail.com
Fixes: 4e645b47c4f0 ("netfilter: core: make nf_unregister_net_hooks simple wrapper again")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: WARNING in geneve_exit_batch_net (2)

[Florian Westphal]

syzbot <syzbot+68a8ed58e3d17c700de5@syzkaller.appspotmail.com> wrote:
> syzbot has bisected this bug to:
> 
> commit 4e645b47c4f000a503b9c90163ad905786b9bc1d
> Author: Florian Westphal <fw@strlen.de>
> Date:   Thu Nov 30 23:21:02 2017 +0000
> 
>     netfilter: core: make nf_unregister_net_hooks simple wrapper again

No idea why this turns up, the reproducer doesn't hit any of these code
paths.

The debug splat is a false-positive; ndo_stop/list_del hasn't run yet.
I will send a fix for net tree.

Re: WARNING in geneve_exit_batch_net (2)

[Dmitry Vyukov]

On Fri, Mar 13, 2020 at 2:45 AM Florian Westphal <fw@strlen.de> wrote:
>
> syzbot <syzbot+68a8ed58e3d17c700de5@syzkaller.appspotmail.com> wrote:
> > syzbot has bisected this bug to:
> >
> > commit 4e645b47c4f000a503b9c90163ad905786b9bc1d
> > Author: Florian Westphal <fw@strlen.de>
> > Date:   Thu Nov 30 23:21:02 2017 +0000
> >
> >     netfilter: core: make nf_unregister_net_hooks simple wrapper again
>
> No idea why this turns up, the reproducer doesn't hit any of these code
> paths.

The attached bisection log usually makes this reasonably transparent.
It seems that in this case another kernel bug gets in the way of bisection.

> The debug splat is a false-positive; ndo_stop/list_del hasn't run yet.
> I will send a fix for net tree.
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20200313014435.GY979%40breakpoint.cc.