syzbot


WARNING in rt6_multipath_rebalance

Status: upstream: reported on 2025/07/04 11:26
Reported-by: syzbot+78db9e9e70426856f776@syzkaller.appspotmail.com
First crash: 38d, last: 16d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in rt6_multipath_rebalance (2) net -1 176 3h12m 102d 0/29 upstream: reported on 2025/05/01 11:16
linux-6.6 WARNING in rt6_multipath_rebalance -1 4 1d22h 17d 0/2 upstream: reported on 2025/07/25 05:47
upstream WARNING in rt6_multipath_rebalance net -1 2 155d 159d 0/29 closed as invalid on 2025/04/08 14:38

Sample crash report:
bridge0: port 2(bridge_slave_1) entered disabled state
device bridge_slave_0 left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
------------[ cut here ]------------
WARNING: CPU: 0 PID: 8608 at net/ipv6/route.c:4796 rt6_multipath_first_sibling net/ipv6/route.c:4718 [inline]
WARNING: CPU: 0 PID: 8608 at net/ipv6/route.c:4796 rt6_multipath_rebalance+0x449/0x8a0 net/ipv6/route.c:4795
Modules linked in:
CPU: 0 PID: 8608 Comm: kworker/u4:24 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
RIP: 0010:rt6_multipath_rebalance+0x449/0x8a0 net/ipv6/route.c:4796
Code: e8 9c bb f1 f8 e9 1c fe ff ff 44 89 e1 80 e1 07 38 c1 0f 8c 85 fe ff ff 4c 89 e7 e8 61 bb f1 f8 e9 78 fe ff ff e8 07 9f a1 f8 <0f> 0b eb 07 e8 fe 9e a1 f8 0f 0b 48 83 c4 10 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90004baf0e0 EFLAGS: 00010293
RAX: ffffffff88df27d9 RBX: ffff888060a92400 RCX: ffff888018533b80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed1003c79c42
R10: ffffed1003c79c42 R11: 1ffff11003c79c41 R12: ffff888055a430be
R13: ffff888060a92480 R14: 0000000000000000 R15: 1ffff1100c152490
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c31fc92 CR3: 000000006587a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 000000000000000e DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 fib6_ifdown+0x3ef/0x4a0 net/ipv6/route.c:4916
 fib6_clean_node+0x244/0x580 net/ipv6/ip6_fib.c:2191
 fib6_walk_continue+0x640/0x8c0 net/ipv6/ip6_fib.c:2116
 fib6_walk+0x149/0x290 net/ipv6/ip6_fib.c:2164
 fib6_clean_tree net/ipv6/ip6_fib.c:2244 [inline]
 __fib6_clean_all+0x231/0x370 net/ipv6/ip6_fib.c:2260
 rt6_sync_down_dev net/ipv6/route.c:4944 [inline]
 rt6_disable_ip+0x120/0x7f0 net/ipv6/route.c:4949
 addrconf_ifdown+0x162/0x1a10 net/ipv6/addrconf.c:3799
 addrconf_notify+0x405/0xf40 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline]
 call_netdevice_notifiers net/core/dev.c:2053 [inline]
 dev_close_many+0x28d/0x400 net/core/dev.c:1601
 unregister_netdevice_many+0x471/0x1840 net/core/dev.c:10952
 default_device_exit_batch+0x9c3/0xa50 net/core/dev.c:11491
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x77b/0xb80 net/core/net_namespace.c:640
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/26 08:55 linux-6.1.y 3594f306da12 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in rt6_multipath_rebalance
2025/07/04 11:25 linux-6.1.y 7e69c33e4858 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in rt6_multipath_rebalance
* Struck through repros no longer work on HEAD.