audit: type=1400 audit(550.489:18627): avc:  denied  { write } for  pid=17267 comm="syz.8.3875" name="sg0" dev="devtmpfs" ino=137 scontext=root:sysadm_r:sysadm_t tcontext=system_u:object_r:scsi_generic_device_t tclass=chr_file permissive=1
audit: type=1400 audit(550.589:18628): avc:  denied  { write } for  pid=17267 comm="syz.8.3875" scontext=root:sysadm_r:sysadm_t tcontext=system_u:system_r:kernel_t tclass=key permissive=1
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff868695f8 of 8 bytes by task 17271 on cpu 1:
 data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8d7/0xad0 kernel/printk/printk_ringbuffer.c:1724
 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
 set_capacity_and_notify+0x1dd/0x230 block/genhd.c:93
 loop_set_size+0x2e/0x70 drivers/block/loop.c:220
 loop_configure+0x828/0x9c0 drivers/block/loop.c:1080
 lo_ioctl+0x1e1/0x12b0 drivers/block/loop.c:1535
 blkdev_ioctl+0x37d/0x460 block/ioctl.c:792
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x14b0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
 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 0xffffffff868695f8 of 8 bytes by task 29 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline]
 prb_reserve+0x207/0xad0 kernel/printk/printk_ringbuffer.c:1674
 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
 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: 0xfffffffffffc3dd8 -> 0x000000000006eee0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 29 Comm: kauditd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================
audit: type=1326 audit(550.609:18629): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=17270 comm="syz.2.3877" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f0b6ee9f749 code=0x7ffc0000
audit: type=1326 audit(550.609:18630): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=17270 comm="syz.2.3877" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f0b6ee9f749 code=0x7ffc0000
audit: type=1326 audit(550.609:18631): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=17270 comm="syz.2.3877" exe="/root/syz-executor" sig=0 arch=c000003e syscall=332 compat=0 ip=0x7f0b6ee9f749 code=0x7ffc0000
audit: type=1326 audit(550.609:18632): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=17270 comm="syz.2.3877" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f0b6ee9f749 code=0x7ffc0000
audit: type=1326 audit(550.609:18633): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=17270 comm="syz.2.3877" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f0b6ee9f749 code=0x7ffc0000