EXT4-fs error (device loop1): ext4_xattr_set_entry:1670: inode #2: comm syz.1.6156: corrupted xattr entries
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BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff89151600 of 1 bytes by task 3300 on cpu 1:
 string_nocheck lib/vsprintf.c:658 [inline]
 string+0x187/0x220 lib/vsprintf.c:736
 vsnprintf+0x532/0x860 lib/vsprintf.c:2947
 vscnprintf+0x41/0x90 lib/vsprintf.c:3012
 printk_sprint+0x30/0x2c0 kernel/printk/printk.c:2194
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2314
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2404
 devkmsg_emit+0x7f/0xb0 kernel/printk/printk.c:733
 devkmsg_write+0x1e2/0x2b0 kernel/printk/printk.c:796
 do_iter_readv_writev+0x4fd/0x5a0 fs/read_write.c:-1
 vfs_writev+0x2e1/0x900 fs/read_write.c:1059
 do_writev+0xe9/0x210 fs/read_write.c:1105
 __do_sys_writev fs/read_write.c:1173 [inline]
 __se_sys_writev fs/read_write.c:1170 [inline]
 __x64_sys_writev+0x45/0x50 fs/read_write.c:1170
 x64_sys_call+0x1c0c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:21
 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

read to 0xffffffff89151600 of 8 bytes by task 17500 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2304
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2404
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2443
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2453
 __ext4_error_inode+0x2af/0x3d0 fs/ext4/super.c:855
 ext4_xattr_set_entry+0x36c/0x1010 fs/ext4/xattr.c:1670
 ext4_xattr_ibody_set+0x184/0x3c0 fs/ext4/xattr.c:2273
 ext4_xattr_set_handle+0xa04/0xf80 fs/ext4/xattr.c:2445
 __ext4_set_acl+0x313/0x380 fs/ext4/acl.c:217
 ext4_set_acl+0x2b8/0x3e0 fs/ext4/acl.c:259
 set_posix_acl fs/posix_acl.c:955 [inline]
 vfs_set_acl+0x615/0x7d0 fs/posix_acl.c:1134
 do_set_acl+0xa9/0x130 fs/posix_acl.c:1279
 do_setxattr fs/xattr.c:633 [inline]
 file_setxattr+0x171/0x1b0 fs/xattr.c:646
 path_setxattrat+0x281/0x310 fs/xattr.c:706
 __do_sys_fsetxattr fs/xattr.c:756 [inline]
 __se_sys_fsetxattr fs/xattr.c:753 [inline]
 __x64_sys_fsetxattr+0x6b/0x80 fs/xattr.c:753
 x64_sys_call+0x2f0e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:191
 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: 0x00000000ffffebd2 -> 0x00000a6d65747379

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 17500 Comm: syz.1.6156 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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