audit: type=1326 audit(1768238471.555:143655): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000
audit: type=1326 audit(1768238471.555:143656): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff8689b120 of 88 bytes by task 3377 on cpu 1:
 prb_reserve+0x6e6/0xad0 kernel/printk/printk_ringbuffer.c:1690
 vprintk_store+0x53c/0x830 kernel/printk/printk.c:2302
 vprintk_emit+0x15a/0x5c0 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
 tbf_change+0xb10/0xc30 net/sched/sch_tbf.c:429
 qdisc_change net/sched/sch_api.c:1381 [inline]
 __tc_modify_qdisc net/sched/sch_api.c:1723 [inline]
 tc_modify_qdisc+0x117e/0x1480 net/sched/sch_api.c:1817
 rtnetlink_rcv_msg+0x65a/0x6d0 net/core/rtnetlink.c:6967
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6985
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 ____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592
 ___sys_sendmsg+0x17b/0x1d0 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+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8689b120 of 8 bytes by task 29 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2014 [inline]
 _prb_read_valid+0x383/0x920 kernel/printk/printk_ringbuffer.c:2171
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2242
 __console_flush_and_unlock kernel/printk/printk.c:3338 [inline]
 console_unlock+0x13c/0x270 kernel/printk/printk.c:3359
 vprintk_emit+0x39f/0x5c0 kernel/printk/printk.c:2426
 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
 kauditd_printk_skb kernel/audit.c:583 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:618
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:803
 kauditd_thread+0x442/0x680 kernel/audit.c:927
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x0000000000002086 -> 0x0000000000004086

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 29 Comm: kauditd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================
audit: type=1326 audit(1768238471.564:143657): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=321 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000
audit: type=1326 audit(1768238471.564:143658): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000
audit: type=1326 audit(1768238471.564:143659): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000
audit: type=1326 audit(1768238471.564:143660): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=321 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000
audit: type=1326 audit(1768238471.583:143661): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=3384 comm="syz.5.11271" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f6ef9f0f749 code=0x7ffc0000