syzbot

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BUG: KCSAN: data-race in __dev_change_flags / xfrm_lookup_with_ifid

read-write to 0xffff8881191190b0 of 4 bytes by task 9039 on cpu 0:
 __dev_change_flags+0x9a/0x400 net/core/dev.c:9432
 netif_change_flags+0x5a/0xd0 net/core/dev.c:9521
 do_setlink+0x9d2/0x2810 net/core/rtnetlink.c:3141
 rtnl_group_changelink net/core/rtnetlink.c:3773 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3927 [inline]
 rtnl_newlink+0xd8b/0x12d0 net/core/rtnetlink.c:4055
 rtnetlink_rcv_msg+0x5fb/0x6d0 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2552
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6971
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5a8/0x680 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x142/0x180 net/socket.c:727
 ____sys_sendmsg+0x31e/0x4e0 net/socket.c:2566
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2655
 x64_sys_call+0x2999/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881191190b0 of 4 bytes by task 9038 on cpu 1:
 xfrm_lookup_with_ifid+0xed3/0x1360 net/xfrm/xfrm_policy.c:3307
 xfrm_lookup net/xfrm/xfrm_policy.c:3336 [inline]
 xfrm_lookup_route+0x3a/0x110 net/xfrm/xfrm_policy.c:3347
 ip_route_output_flow+0xf1/0x130 net/ipv4/route.c:2928
 raw_sendmsg+0x9f5/0xe50 net/ipv4/raw.c:628
 inet_sendmsg+0xc2/0xd0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x102/0x180 net/socket.c:727
 ____sys_sendmsg+0x345/0x4e0 net/socket.c:2566
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2620
 __sys_sendmmsg+0x178/0x300 net/socket.c:2709
 __do_sys_sendmmsg net/socket.c:2736 [inline]
 __se_sys_sendmmsg net/socket.c:2733 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2733
 x64_sys_call+0x2f2f/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:308
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000081 -> 0x00001021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9038 Comm: syz.6.1946 Tainted: G        W           6.16.0-rc7-syzkaller-00140-gec2df4364666 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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