xt_hashlimit: size too large, truncated to 1048576
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff8912ea30 of 45 bytes by task 18379 on cpu 1:
 vsnprintf+0x2ce/0x860 lib/vsprintf.c:2898
 vscnprintf+0x41/0x90 lib/vsprintf.c:3012
 printk_sprint+0x30/0x2c0 kernel/printk/printk.c:2192
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2312
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 hashlimit_mt_check_common+0x448/0x6c0 net/netfilter/xt_hashlimit.c:852
 hashlimit_mt_check+0x64/0x80 net/netfilter/xt_hashlimit.c:957
 xt_check_match+0x2ad/0x4f0 net/netfilter/x_tables.c:523
 check_match net/ipv6/netfilter/ip6_tables.c:488 [inline]
 find_check_match net/ipv6/netfilter/ip6_tables.c:505 [inline]
 find_check_entry net/ipv6/netfilter/ip6_tables.c:556 [inline]
 translate_table+0xbc1/0x11b0 net/ipv6/netfilter/ip6_tables.c:733
 do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
 do_ip6t_set_ctl+0x6d9/0x8f0 net/ipv6/netfilter/ip6_tables.c:1644
 nf_setsockopt+0x199/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x11a/0x130 net/ipv6/ipv6_sockglue.c:978
 rawv6_setsockopt+0x1d2/0x410 net/ipv6/raw.c:1047
 sock_common_setsockopt+0x69/0x80 net/core/sock.c:3973
 do_sock_setsockopt net/socket.c:2322 [inline]
 __sys_setsockopt+0x184/0x200 net/socket.c:2347
 __do_sys_setsockopt net/socket.c:2353 [inline]
 __se_sys_setsockopt net/socket.c:2350 [inline]
 __x64_sys_setsockopt+0x64/0x80 net/socket.c:2350
 x64_sys_call+0x21d5/0x3000 arch/x86/include/generated/asm/syscalls_64.h:55
 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 0xffffffff8912ea50 of 8 bytes by task 18378 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2302
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 hashlimit_mt_check_common+0x448/0x6c0 net/netfilter/xt_hashlimit.c:852
 hashlimit_mt_check+0x64/0x80 net/netfilter/xt_hashlimit.c:957
 xt_check_match+0x2ad/0x4f0 net/netfilter/x_tables.c:523
 check_match net/ipv6/netfilter/ip6_tables.c:488 [inline]
 find_check_match net/ipv6/netfilter/ip6_tables.c:505 [inline]
 find_check_entry net/ipv6/netfilter/ip6_tables.c:556 [inline]
 translate_table+0xbc1/0x11b0 net/ipv6/netfilter/ip6_tables.c:733
 do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
 do_ip6t_set_ctl+0x6d9/0x8f0 net/ipv6/netfilter/ip6_tables.c:1644
 nf_setsockopt+0x199/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x11a/0x130 net/ipv6/ipv6_sockglue.c:978
 rawv6_setsockopt+0x1d2/0x410 net/ipv6/raw.c:1047
 sock_common_setsockopt+0x69/0x80 net/core/sock.c:3973
 do_sock_setsockopt net/socket.c:2322 [inline]
 __sys_setsockopt+0x184/0x200 net/socket.c:2347
 __do_sys_setsockopt net/socket.c:2353 [inline]
 __se_sys_setsockopt net/socket.c:2350 [inline]
 __x64_sys_setsockopt+0x64/0x80 net/socket.c:2350
 x64_sys_call+0x21d5/0x3000 arch/x86/include/generated/asm/syscalls_64.h:55
 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: 0x00000000fffff375 -> 0x657461636e757274

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 18378 Comm: syz.5.3416 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================