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andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: d8674294aefe Merge git://git.kernel.org/pub/scm/linux/kern.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=14b756d1580000 kernel config: https://syzkaller.appspot.com/x/.config?x=97c5d7b57925a2ec dashboard link: https://syzkaller.appspot.com/bug?extid=751b587577d0ebca10f2 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12b756d1580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11828f15580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/4b49acf0cec9/disk-d8674294.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2d7502d8747e/vmlinux-d8674294.xz kernel image: https://storage.googleapis.com/syzbot-assets/706ef88ff29f/bzImage-d8674294.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+751b587577d0ebca10f2@syzkaller.appspotmail.com ------------[ cut here ]------------ i != fen6_info->nsiblings WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib6_event_init drivers/net/netdevsim/fib.c:831 [inline], CPU#0: syz.0.157/6279 WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib6_prepare_event drivers/net/netdevsim/fib.c:947 [inline], CPU#0: syz.0.157/6279 WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1003 [inline], CPU#0: syz.0.157/6279 WARNING: drivers/net/netdevsim/fib.c:831 at nsim_fib_event_nb+0x1029/0x11d0 drivers/net/netdevsim/fib.c:1043, CPU#0: syz.0.157/6279 Modules linked in: CPU: 0 UID: 0 PID: 6279 Comm: syz.0.157 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:nsim_fib6_event_init drivers/net/netdevsim/fib.c:831 [inline] RIP: 0010:nsim_fib6_prepare_event drivers/net/netdevsim/fib.c:947 [inline] RIP: 0010:nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1003 [inline] RIP: 0010:nsim_fib_event_nb+0x1029/0x11d0 drivers/net/netdevsim/fib.c:1043 Code: eb 0d 4d 89 fd e8 b7 c5 6c fa be 01 00 00 00 48 89 df e8 5a 38 85 fd 4d 89 ef 4c 8b 6c 24 20 e9 4a f3 ff ff e8 98 c5 6c fa 90 <0f> 0b 90 e9 db fa ff ff 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c df f0 RSP: 0018:ffffc900047bef10 EFLAGS: 00010293 RAX: ffffffff875b59a8 RBX: 0000000000000002 RCX: ffff888079770000 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001 RBP: ffffc900047bf0a0 R08: ffff88805c0bb02f R09: 1ffff1100b817605 R10: dffffc0000000000 R11: ffffed100b817606 R12: dffffc0000000000 R13: 0000000000000000 R14: 0000000000000001 R15: ffff88802c792000 FS: 00007f334ba076c0(0000) GS:ffff888123ad0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f334ba06ff8 CR3: 000000007a5b2000 CR4: 00000000003526f0 Call Trace: notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:223 call_fib_notifiers+0x31/0x60 net/core/fib_notifier.c:36 call_fib6_multipath_entry_notifiers+0xf5/0x160 net/ipv6/ip6_fib.c:428 ip6_route_multipath_add net/ipv6/route.c:5542 [inline] inet6_rtm_newroute+0x14f5/0x1a30 net/ipv6/route.c:5664 rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7163 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800 __sock_sendmsg net/socket.c:818 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2715 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2769 __sys_sendmmsg+0x273/0x4d0 net/socket.c:2858 __do_sys_sendmmsg net/socket.c:2885 [inline] __se_sys_sendmmsg net/socket.c:2882 [inline] __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2882 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f334ab9e1d9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f334ba07028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f334ae26090 RCX: 00007f334ab9e1d9 RDX: 04000000000001f2 RSI: 0000200000000000 RDI: 0000000000000004 RBP: 00007f334ac35888 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000000000fc R11: 0000000000000246 R12: 0000000000000000 R13: 00007f334ae26128 R14: 00007f334ae26090 R15: 00007ffd96688aa8 --- This report 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 issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup