[syzbot] [net?] WARNING: suspicious RCU usage in xfrm_send_migrate_state

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 365f9c7a6b81 Merge branches 'for-next/core' and 'for-next/..
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=14863632580000
kernel config: https://syzkaller.appspot.com/x/.config?x=72c97575381cec47
dashboard link: https://syzkaller.appspot.com/bug?extid=b9e97485773456b16a4a
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=12863632580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11b0e49e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eafe0adb7386/disk-365f9c7a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/29422d607579/vmlinux-365f9c7a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/98ca955a8b54/Image-365f9c7a.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b9e974...@syzkaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
net/xfrm/xfrm_user.c:1630 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz.0.17/4942:
#0: ffff0000d8a19c50 (&net->xfrm.xfrm_cfg_mutex){+.+.}-{4:4}, at: xfrm_netlink_rcv+0x70/0x9c net/xfrm/xfrm_user.c:3928

stack backtrace:
CPU: 0 UID: 0 PID: 4942 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
__dump_stack+0x30/0x40 lib/dump_stack.c:94
dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
dump_stack+0x1c/0x28 lib/dump_stack.c:129
lockdep_rcu_suspicious+0x168/0x26c kernel/locking/lockdep.c:6876
xfrm_nlmsg_multicast net/xfrm/xfrm_user.c:1630 [inline]
xfrm_send_migrate_state+0x6b0/0x958 net/xfrm/xfrm_user.c:3340
xfrm_do_migrate_state+0x1114/0x1728 net/xfrm/xfrm_user.c:3507
xfrm_user_rcv_msg+0x4e0/0x950 net/xfrm/xfrm_user.c:3907
netlink_rcv_skb+0x238/0x414 net/netlink/af_netlink.c:2556
xfrm_netlink_rcv+0x80/0x9c net/xfrm/xfrm_user.c:3929
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x600/0x7f8 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x648/0x948 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec net/socket.c:775 [inline]
__sock_sendmsg+0xc8/0x17c net/socket.c:790
____sys_sendmsg+0x3d0/0x6c8 net/socket.c:2684
___sys_sendmsg+0x198/0x224 net/socket.c:2738
__sys_sendmsg+0x158/0x204 net/socket.c:2770
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2773
__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+0x64/0x260 arch/arm64/kernel/entry-common.c:736
el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594


---
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[Aleksandr Nogikh]

#syz dup: WARNING: suspicious RCU usage in xfrm_nlmsg_multicast

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