syzbot

FAT-fs (loop3): Directory bread(block 199916) failed
==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff8936e1e8 of 1 bytes by task 28 on cpu 1:
 number+0x97f/0xb90 lib/vsprintf.c:573
 vsnprintf+0x64e/0x860 lib/vsprintf.c:2912
 vscnprintf+0x41/0x90 lib/vsprintf.c:3013
 printk_sprint+0x30/0x2b0 kernel/printk/printk.c:2222
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2364
 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
 kauditd_printk_skb kernel/audit.c:587 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:622
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:807
 kauditd_thread+0x444/0x670 kernel/audit.c:931
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff8936e1e8 of 8 bytes by task 7024 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+0x8d6/0xad0 kernel/printk/printk_ringbuffer.c:1727
 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
 _fat_msg+0xb0/0xe0 fs/fat/misc.c:62
 fat__get_entry fs/fat/dir.c:104 [inline]
 fat_get_entry+0x52b/0x5d0 fs/fat/dir.c:130
 fat_get_short_entry fs/fat/dir.c:888 [inline]
 fat_subdirs+0x59/0x190 fs/fat/dir.c:954
 fat_read_root+0x32e/0x370 fs/fat/inode.c:1351
 fat_fill_super+0x14c5/0x1c10 fs/fat/inode.c:1824
 vfat_fill_super+0x24/0x30 fs/fat/namei_vfat.c:1202
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1694
 get_tree_bdev+0x1f/0x30 fs/super.c:1717
 vfat_get_tree+0x1c/0x30 fs/fat/namei_vfat.c:1207
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3834
 path_mount+0x4d0/0xbc0 fs/namespace.c:4154
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4360
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4360
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x3fffffffffffe074 -> 0x3428746964756120

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7024 Comm: syz.3.1690 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================
FAT-fs (loop3): Directory bread(block 199917) failed
FAT-fs (loop3): Directory bread(block 199918) failed
FAT-fs (loop3): Directory bread(block 199919) failed
FAT-fs (loop3): Directory bread(block 199920) failed
FAT-fs (loop3): Directory bread(block 199921) failed
FAT-fs (loop3): Directory bread(block 199922) failed
FAT-fs (loop3): Directory bread(block 199923) failed