[syzbot] [net?] WARNING in __skb_flow_dissect (8)

[syzbot <syzbot+9408fbe0e6452a12e9ab@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    e8e60d3ddd25 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=14800605580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=375776a45e10c065
dashboard link: https://syzkaller.appspot.com/bug?extid=9408fbe0e6452a12e9ab
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12800605580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=138b2605580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ca9fd6dc9b6c/disk-e8e60d3d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/690b32d87cdf/vmlinux-e8e60d3d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/35db39da550c/Image-e8e60d3d.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9408fbe0e6452a12e9ab@syzkaller.appspotmail.com

tipc: Started in network mode
tipc: Node identity ac14143b, cluster identity 4711
tipc: New replicast peer: 10.1.1.0
------------[ cut here ]------------
WARNING: net/core/flow_dissector.c:1131 at __skb_flow_dissect+0x910/0x5368 net/core/flow_dissector.c:1126, CPU#1: syz.0.17/4912
Modules linked in:
CPU: 1 UID: 0 PID: 4912 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __skb_flow_dissect+0x910/0x5368 net/core/flow_dissector.c:1126
lr : __skb_flow_dissect+0x910/0x5368 net/core/flow_dissector.c:1126
sp : ffff800094906200
x29: ffff800094906700 x28: 0000000000000000 x27: 0000000000000002
x26: 0000000000000000 x25: ffff0000d05fd3c0 x24: dfff800000000000
x23: 0000000000000000 x22: 1ffff0001114beb7 x21: ffff800088a5f5b0
x20: 0000000000000000 x19: ffff700012920c58 x18: 00000000ffffffff
x17: ffff8000863d2120 x16: ffff8000863d32f4 x15: ffff80008a707000
x14: 000000000064059a x13: 0000000000000009 x12: 0000000000000009
x11: 00000000d6794b26 x10: 0000000000000003 x9 : 0000000000000400
x8 : 0000000000000000 x7 : ffff800084c05fcc x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800084c05fe8
x2 : 0000000000000001 x1 : ffff0000c46c9d80 x0 : 0000000000000000
Call trace:
 __skb_flow_dissect+0x910/0x5368 net/core/flow_dissector.c:1126 (P)
 __skb_get_hash_net+0xe0/0x29c net/core/flow_dissector.c:1903
 skb_get_hash include/linux/skbuff.h:1663 [inline]
 seg6_make_flowlabel+0xcc/0x1ec net/ipv6/seg6_iptunnel.c:132
 __seg6_do_srh_encap+0x320/0xbf4 net/ipv6/seg6_iptunnel.c:161
 seg6_do_srh+0x4b4/0xa44 net/ipv6/seg6_iptunnel.c:431
 seg6_output_core+0x164/0x688 net/ipv6/seg6_iptunnel.c:681
 seg6_output+0x44/0x1ac net/ipv6/seg6_iptunnel.c:744
 lwtunnel_output+0x3d0/0x664 net/core/lwtunnel.c:356
 dst_output include/net/dst.h:470 [inline]
 ip_local_out+0x110/0x148 net/ipv4/ip_output.c:131
 iptunnel_xmit+0x50c/0xd38 net/ipv4/ip_tunnel_core.c:97
 udp_tunnel_xmit_skb+0x220/0x348 net/ipv4/udp_tunnel_core.c:187
 tipc_udp_xmit+0x75c/0x9c0 net/tipc/udp_media.c:202
 tipc_udp_send_msg+0x214/0x374 net/tipc/udp_media.c:274
 tipc_bearer_xmit_skb+0x260/0x3b0 net/tipc/bearer.c:576
 tipc_enable_bearer net/tipc/bearer.c:366 [inline]
 __tipc_nl_bearer_enable+0xc90/0xfb0 net/tipc/bearer.c:1048
 tipc_nl_bearer_enable+0x2c/0x48 net/tipc/bearer.c:1057
 genl_family_rcv_msg_doit+0x1e4/0x2d4 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x43c/0x620 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x238/0x414 net/netlink/af_netlink.c:2575
 genl_rcv+0x38/0x50 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
 netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1364
 netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg+0xc8/0x17c net/socket.c:815
 ____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2713
 ___sys_sendmsg+0x198/0x224 net/socket.c:2767
 __sys_sendmsg+0x158/0x204 net/socket.c:2799
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __arm64_sys_sendmsg+0x88/0x9c net/socket.c:2802
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606
irq event stamp: 1573
hardirqs last  enabled at (1572): [<ffff80008030a2b4>] __local_bh_enable_ip+0x14c/0x234 kernel/softirq.c:478
hardirqs last disabled at (1573): [<ffff80008685dbf4>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:483
softirqs last  enabled at (1546): [<ffff800084bb85e4>] __alloc_skb+0x1c0/0x610 net/core/skbuff.c:698
softirqs last disabled at (1552): [<ffff8000863d31fc>] local_bh_disable include/linux/bottom_half.h:20 [inline]
softirqs last disabled at (1552): [<ffff8000863d31fc>] tipc_udp_xmit+0xb8/0x9c0 net/tipc/udp_media.c:181
---[ end trace 0000000000000000 ]---
tipc: Enabled bearer <udp:syz1>, priority 10


---
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