==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff86d91588 of 1 bytes by task 26643 on cpu 0:
 number+0x8f5/0xb60 lib/vsprintf.c:556
 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2871
 vscnprintf+0x29/0x80 lib/vsprintf.c:2908
 printk_sprint kernel/printk/printk.c:2076 [inline]
 vprintk_store+0x638/0xbb0 kernel/printk/printk.c:2186
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 __show_regs+0x63/0x330 arch/x86/kernel/process_64.c:81
 show_regs_if_on_stack arch/x86/kernel/dumpstack.c:173 [inline]
 show_trace_log_lvl+0x5b8/0x670 arch/x86/kernel/dumpstack.c:298
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd6/0x122 lib/dump_stack.c:106
 dump_stack+0x11/0x1b lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23c/0x250 lib/fault-inject.c:146
 should_fail_usercopy+0x16/0x20 lib/fault-inject-usercopy.c:37
 _copy_from_user+0x1c/0xd0 lib/usercopy.c:14
 copy_from_user include/linux/uaccess.h:192 [inline]
 copy_from_sockptr_offset include/linux/sockptr.h:48 [inline]
 copy_from_bpfptr_offset include/linux/bpfptr.h:52 [inline]
 copy_from_bpfptr include/linux/bpfptr.h:57 [inline]
 __sys_bpf+0x1d4/0xa3f0 kernel/bpf/syscall.c:4606
 __do_sys_bpf kernel/bpf/syscall.c:4737 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4735 [inline]
 __x64_sys_bpf+0x3f/0x50 kernel/bpf/syscall.c:4735
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff86d91588 of 8 bytes by task 26644 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x138/0x470 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x920/0xbf0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x560/0xbb0 kernel/printk/printk.c:2176
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x223/0x250 lib/fault-inject.c:146
 __should_failslab+0x81/0x90 mm/failslab.c:33
 should_failslab+0x5/0x20 mm/slab_common.c:1320
 slab_pre_alloc_hook mm/slab.h:494 [inline]
 slab_alloc mm/slab.c:3306 [inline]
 __do_kmalloc mm/slab.c:3700 [inline]
 __kmalloc_track_caller+0x6d/0x370 mm/slab.c:3717
 __do_krealloc mm/slab_common.c:1200 [inline]
 krealloc+0x3f/0xa0 mm/slab_common.c:1233
 nf_ct_ext_add+0x145/0x1f0 net/netfilter/nf_conntrack_extend.c:73
 nf_ct_labels_ext_add include/net/netfilter/nf_conntrack_labels.h:37 [inline]
 init_conntrack+0x56f/0xb30 net/netfilter/nf_conntrack_core.c:1653
 resolve_normal_ct+0x502/0x610 net/netfilter/nf_conntrack_core.c:1746
 nf_conntrack_in+0x1c5/0x88f net/netfilter/nf_conntrack_core.c:1901
 ipv6_conntrack_local+0x19/0x20 net/netfilter/nf_conntrack_proto.c:414
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0x72/0x170 net/netfilter/core.c:619
 nf_hook include/linux/netfilter.h:262 [inline]
 __ip6_local_out+0x22c/0x250 net/ipv6/output_core.c:149
 ip6_local_out+0x22/0x80 net/ipv6/output_core.c:159
 ip6_send_skb+0x43/0xf0 net/ipv6/ip6_output.c:1912
 udp_v6_send_skb+0x798/0x9f0 net/ipv6/udp.c:1249
 udpv6_sendmsg+0x1669/0x16e0 net/ipv6/udp.c:1547
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:644
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2409
 ___sys_sendmsg net/socket.c:2463 [inline]
 __sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
 __do_sys_sendmmsg net/socket.c:2578 [inline]
 __se_sys_sendmmsg net/socket.c:2575 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000fffff242 -> 0x3a58435220303666

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26644 Comm: syz-executor.1 Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
CPU: 1 PID: 26644 Comm: syz-executor.1 Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd6/0x122 lib/dump_stack.c:106
 dump_stack+0x11/0x1b lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23c/0x250 lib/fault-inject.c:146
 __should_failslab+0x81/0x90 mm/failslab.c:33
 should_failslab+0x5/0x20 mm/slab_common.c:1320
 slab_pre_alloc_hook mm/slab.h:494 [inline]
 slab_alloc mm/slab.c:3306 [inline]
 __do_kmalloc mm/slab.c:3700 [inline]
 __kmalloc_track_caller+0x6d/0x370 mm/slab.c:3717
 __do_krealloc mm/slab_common.c:1200 [inline]
 krealloc+0x3f/0xa0 mm/slab_common.c:1233
 nf_ct_ext_add+0x145/0x1f0 net/netfilter/nf_conntrack_extend.c:73
 nf_ct_labels_ext_add include/net/netfilter/nf_conntrack_labels.h:37 [inline]
 init_conntrack+0x56f/0xb30 net/netfilter/nf_conntrack_core.c:1653
 resolve_normal_ct+0x502/0x610 net/netfilter/nf_conntrack_core.c:1746
 nf_conntrack_in+0x1c5/0x88f net/netfilter/nf_conntrack_core.c:1901
 ipv6_conntrack_local+0x19/0x20 net/netfilter/nf_conntrack_proto.c:414
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0x72/0x170 net/netfilter/core.c:619
 nf_hook include/linux/netfilter.h:262 [inline]
 __ip6_local_out+0x22c/0x250 net/ipv6/output_core.c:149
 ip6_local_out+0x22/0x80 net/ipv6/output_core.c:159
 ip6_send_skb+0x43/0xf0 net/ipv6/ip6_output.c:1912
 udp_v6_send_skb+0x798/0x9f0 net/ipv6/udp.c:1249
 udpv6_sendmsg+0x1669/0x16e0 net/ipv6/udp.c:1547
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:644
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2409
 ___sys_sendmsg net/socket.c:2463 [inline]
 __sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
 __do_sys_sendmmsg net/socket.c:2578 [inline]
 __se_sys_sendmmsg net/socket.c:2575 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f622841fae9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6226196188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f6228532f60 RCX: 00007f622841fae9
RDX: 00000000000004ff RSI: 00000000200092c0 RDI: 0000000000000004
RBP: 00007f62261961d0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000003e8 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc149d29af R14: 00007f6226196300 R15: 0000000000022000
 </TASK>
syz-executor.1 (26644) used greatest stack depth: 9520 bytes left