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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff868f1058 of 88 bytes by task 4012 on cpu 0:
 prb_reserve+0x696/0xaf0 kernel/printk/printk_ringbuffer.c:1635
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 __ext4_error_inode+0x2ca/0x3f0 fs/ext4/super.c:844
 check_xattrs+0x25e/0x7d0 fs/ext4/xattr.c:289
 __ext4_xattr_check_block fs/ext4/xattr.c:303 [inline]
 ext4_xattr_block_get fs/ext4/xattr.c:593 [inline]
 ext4_xattr_get+0x1ed/0x470 fs/ext4/xattr.c:708
 ext4_xattr_security_get+0x32/0x40 fs/ext4/xattr_security.c:20
 __vfs_getxattr+0x2ad/0x2c0 fs/xattr.c:423
 inode_doinit_use_xattr+0x7a/0x2d0 security/selinux/hooks.c:1371
 inode_doinit_with_dentry+0x596/0x7a0 security/selinux/hooks.c:1496
 __inode_security_revalidate security/selinux/hooks.c:296 [inline]
 inode_security_rcu security/selinux/hooks.c:314 [inline]
 selinux_inode_permission+0x1d7/0x740 security/selinux/hooks.c:3216
 security_inode_permission+0x6d/0xb0 security/security.c:2324
 inode_permission+0x106/0x310 fs/namei.c:601
 may_open+0x255/0x350 fs/namei.c:3477
 do_open fs/namei.c:3885 [inline]
 path_openat+0x1b4a/0x2170 fs/namei.c:4046
 do_filp_open+0x109/0x230 fs/namei.c:4073
 do_sys_openat2+0xa6/0x110 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_open fs/open.c:1458 [inline]
 __se_sys_open fs/open.c:1454 [inline]
 __x64_sys_open+0xe6/0x110 fs/open.c:1454
 x64_sys_call+0x1457/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:3
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff868f1058 of 8 bytes by task 4097 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1874 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x1c4/0x920 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2185
 __console_flush_and_unlock kernel/printk/printk.c:3304 [inline]
 console_unlock+0x164/0x330 kernel/printk/printk.c:3325
 con_flush_chars+0xb2/0x1b0 drivers/tty/vt/vt.c:3587
 __receive_buf drivers/tty/n_tty.c:1628 [inline]
 n_tty_receive_buf_common+0x93d/0xbe0 drivers/tty/n_tty.c:1723
 n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1763
 tiocsti+0x170/0x1d0 drivers/tty/tty_io.c:2290
 tty_ioctl+0x4a4/0xb80 drivers/tty/tty_io.c:2706
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:584
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
 x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000003037 -> 0x0000000000005037

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4097 Comm: syz.1.23169 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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