[syzbot] [net?] WARNING in xfrm6_tunnel_net_exit (4)

[syzbot] [net?] WARNING in xfrm6_tunnel_net_exit (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    8765f467912f Merge tag 'irq_urgent_for_v6.18_rc1' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16eb5b34580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9ad7b090a18654a7
dashboard link: https://syzkaller.appspot.com/bug?extid=3df59a64502c71cab3d5
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/afb0dad890ad/disk-8765f467.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/620faf492b85/vmlinux-8765f467.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7784fba6e17c/bzImage-8765f467.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3df59a64502c71cab3d5@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 12 at net/ipv6/xfrm6_tunnel.c:341 xfrm6_tunnel_net_exit+0x7e/0x100 net/ipv6/xfrm6_tunnel.c:341
Modules linked in:
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: netns cleanup_net
RIP: 0010:xfrm6_tunnel_net_exit+0x7e/0x100 net/ipv6/xfrm6_tunnel.c:341
Code: 38 44 12 f8 4b 83 3c 2c 00 75 19 e8 0c 94 ac f7 49 81 fd f8 07 00 00 74 1d e8 fe 93 ac f7 49 83 c5 08 eb c9 e8 f3 93 ac f7 90 <0f> 0b 90 49 81 fd f8 07 00 00 75 e3 48 81 c3 00 08 00 00 45 31 f6
RSP: 0018:ffffc90000117890 EFLAGS: 00010293
RAX: ffffffff8a13affd RBX: ffff8880403b4000 RCX: ffff88801c2bdac0
RDX: 0000000000000000 RSI: ffffffff8d7e835a RDI: ffff8880403b40b8
RBP: ffffc90000117990 R08: ffffffff8f9e1177 R09: 1ffffffff1f3c22e
R10: dffffc0000000000 R11: fffffbfff1f3c22f R12: ffff8880403b4000
R13: 00000000000000b8 R14: ffff88805ae1a480 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888125d0c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3845a0 CR3: 000000003cee6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49a/0x990 net/core/net_namespace.c:252
 cleanup_net+0x4d8/0x820 net/core/net_namespace.c:695
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
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If the report is already addressed, let syzbot know by replying with:
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If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [net?] WARNING in xfrm6_tunnel_net_exit (4)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    cf1ea8854e4f Merge tag 'mmc-v6.18-rc1' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14b96492580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=af9170887d81dea1
dashboard link: https://syzkaller.appspot.com/bug?extid=3df59a64502c71cab3d5
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=162c3de2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a6a5b37662b9/disk-cf1ea885.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b4d732ae480/vmlinux-cf1ea885.xz
kernel image: https://storage.googleapis.com/syzbot-assets/acd7feec5537/bzImage-cf1ea885.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3df59a64502c71cab3d5@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 12 at net/ipv6/xfrm6_tunnel.c:341 xfrm6_tunnel_net_exit+0x7e/0x100 net/ipv6/xfrm6_tunnel.c:341
Modules linked in:
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: netns cleanup_net
RIP: 0010:xfrm6_tunnel_net_exit+0x7e/0x100 net/ipv6/xfrm6_tunnel.c:341
Code: e8 66 90 f8 4b 83 3c 2c 00 75 19 e8 dc b4 2e f8 49 81 fd f8 07 00 00 74 1d e8 ce b4 2e f8 49 83 c5 08 eb c9 e8 c3 b4 2e f8 90 <0f> 0b 90 49 81 fd f8 07 00 00 75 e3 48 81 c3 00 08 00 00 45 31 f6
RSP: 0018:ffffc90000117890 EFLAGS: 00010293
RAX: ffffffff8990486d RBX: ffff888030f5c000 RCX: ffff88801ba9da00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000117990 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1deee6f R12: ffff888030f5c000
R13: 00000000000003f0 R14: ffff888038a38000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888126bc6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd8ab2e0890 CR3: 00000000338be000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49a/0x990 net/core/net_namespace.c:252
 cleanup_net+0x4de/0x820 net/core/net_namespace.c:695
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [net?] WARNING in xfrm6_tunnel_net_exit (4)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+3df59a64502c71cab3d5@syzkaller.appspotmail.com
Tested-by: syzbot+3df59a64502c71cab3d5@syzkaller.appspotmail.com

Tested on:

commit:         211ddde0 Linux 6.18-rc2
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1564dde2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=af9170887d81dea1
dashboard link: https://syzkaller.appspot.com/bug?extid=3df59a64502c71cab3d5
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1450dde2580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [net?] WARNING in xfrm6_tunnel_net_exit (4)

[syzbot]

syzbot has bisected this issue to:

commit b441cf3f8c4b8576639d20c8eb4aa32917602ecd
Author: Sabrina Dubroca <sd@queasysnail.net>
Date:   Fri Jul 4 14:54:33 2025 +0000

    xfrm: delete x->tunnel as we delete x

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=160c5d2f980000
start commit:   cf1ea8854e4f Merge tag 'mmc-v6.18-rc1' of git://git.kernel..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=150c5d2f980000
console output: https://syzkaller.appspot.com/x/log.txt?x=110c5d2f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=af9170887d81dea1
dashboard link: https://syzkaller.appspot.com/bug?extid=3df59a64502c71cab3d5
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=162c3de2580000

Reported-by: syzbot+3df59a64502c71cab3d5@syzkaller.appspotmail.com
Fixes: b441cf3f8c4b ("xfrm: delete x->tunnel as we delete x")

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