==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86cad338 of 88 bytes by task 15571 on cpu 0:
 prb_reserve+0x6e6/0xae0 kernel/printk/printk_ringbuffer.c:1690
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __netdev_printk+0x310/0x370 net/core/dev.c:12959
 netdev_info+0xa6/0xd0 net/core/dev.c:13006
 __dev_set_promiscuity+0x1fb/0x3f0 net/core/dev.c:9593
 netif_set_promiscuity+0x39/0x90 net/core/dev.c:9628
 dev_set_promiscuity+0xc1/0x170 net/core/dev_api.c:287
 hsr_del_port+0x13b/0x1a0 net/hsr/hsr_slave.c:244
 hsr_del_ports+0x31/0xc0 net/hsr/hsr_device.c:471
 hsr_dellink+0x5b/0xa0 net/hsr/hsr_netlink.c:142
 default_device_exit_batch+0x45c/0x640 net/core/dev.c:13081
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x2ca/0x420 net/core/net_namespace.c:252
 cleanup_net+0x37c/0x5b0 net/core/net_namespace.c:704
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0x513/0xa10 kernel/workqueue.c:3359
 worker_thread+0x58a/0x780 kernel/workqueue.c:3440
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff86cad338 of 8 bytes by task 32370 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2014 [inline]
 _prb_read_valid+0x383/0x950 kernel/printk/printk_ringbuffer.c:2171
 prb_first_valid_seq+0x35/0x70 kernel/printk/printk_ringbuffer.c:2299
 devkmsg_open+0x174/0x1b0 kernel/printk/printk.c:945
 memory_open+0xca/0xf0 drivers/char/mem.c:740
 chrdev_open+0x2eb/0x3a0 fs/char_dev.c:411
 do_dentry_open+0x4ca/0xa90 fs/open.c:949
 vfs_open+0x37/0x1e0 fs/open.c:1081
 do_open fs/namei.c:4677 [inline]
 path_openat+0x1b70/0x2050 fs/namei.c:4836
 do_file_open+0x16c/0x290 fs/namei.c:4865
 do_sys_openat2+0x94/0x130 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1383
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000023d1 -> 0x00000000000043d1

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 32370 Comm: fido_id Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
==================================================================
fido_id[32370]: Failed to open report descriptor at '/sys/devices/virtual/misc/uhid/report_descriptor': No such file or directory