[moderation] [netfilter?] KCSAN: data-race in hash_ipportip4_add / hash_ipportip4_head

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c072629f05d7 Merge tag 'v6.19-p4' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=158cff9a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c9e86480ac654d3
dashboard link: https://syzkaller.appspot.com/bug?extid=5658eefe2ab947b470fd
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [core...@netfilter.org da...@davemloft.net edum...@google.com f...@strlen.de ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org netfilt...@vger.kernel.org pab...@redhat.com pa...@netfilter.org ph...@nwl.cc]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d532c6676f24/disk-c072629f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ae6963bee844/vmlinux-c072629f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90fbb9a24cec/bzImage-c072629f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5658ee...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in hash_ipportip4_add / hash_ipportip4_head

read-write to 0xffff888136071719 of 1 bytes by task 17467 on cpu 1:
hash_ipportip4_add+0x7e1/0x10a0 net/netfilter/ipset/ip_set_hash_gen.h:965
hash_ipportip4_uadt+0x789/0x8b0 net/netfilter/ipset/ip_set_hash_ipportip.c:195
call_ad+0x231/0x640 net/netfilter/ipset/ip_set_core.c:1751
ip_set_ad+0x5c0/0x690 net/netfilter/ipset/ip_set_core.c:1841
ip_set_uadd+0x41/0x50 net/netfilter/ipset/ip_set_core.c:1864
nfnetlink_rcv_msg+0x509/0x5d0 net/netfilter/nfnetlink.c:302
netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
nfnetlink_rcv+0x167/0x1720 net/netfilter/nfnetlink.c:669
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x145/0x170 net/socket.c:742
____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592
___sys_sendmsg+0x195/0x1e0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888136071719 of 1 bytes by task 17470 on cpu 0:
hash_ipportip4_ext_size net/netfilter/ipset/ip_set_hash_gen.h:823 [inline]
hash_ipportip4_head+0x28f/0x790 net/netfilter/ipset/ip_set_hash_gen.h:1276
ip_set_dump_do+0xa34/0xb00 net/netfilter/ipset/ip_set_core.c:1651
netlink_dump+0x455/0x8a0 net/netlink/af_netlink.c:2325
netlink_recvmsg+0x420/0x550 net/netlink/af_netlink.c:1976
sock_recvmsg_nosec net/socket.c:1078 [inline]
sock_recvmsg+0x139/0x160 net/socket.c:1100
____sys_recvmsg+0xf5/0x280 net/socket.c:2812
___sys_recvmsg+0x11f/0x3b0 net/socket.c:2854
__sys_recvmsg net/socket.c:2887 [inline]
__do_sys_recvmsg net/socket.c:2893 [inline]
__se_sys_recvmsg net/socket.c:2890 [inline]
__x64_sys_recvmsg+0xd1/0x160 net/socket.c:2890
x64_sys_call+0x2cbf/0x3000 arch/x86/include/generated/asm/syscalls_64.h:48
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01 -> 0x02

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 17470 Comm: syz.6.3953 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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