syzbot

FAT-fs (loop3): bogus number of reserved sectors
==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff8708fd40 of 8 bytes by task 12843 on cpu 0:
 data_alloc+0x205/0x2b0 kernel/printk/printk_ringbuffer.c:1074
 prb_reserve+0x897/0xbd0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x51c/0xb50 kernel/printk/printk.c:2196
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2282
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2292
 _fat_msg+0xad/0xd1 fs/fat/misc.c:62
 fat_read_bpb fs/fat/inode.c:1488 [inline]
 fat_fill_super+0x140f/0x26c0 fs/fat/inode.c:1657
 vfat_fill_super+0x2c/0x40 fs/fat/namei_vfat.c:1200
 mount_bdev+0x1e2/0x280 fs/super.c:1400
 vfat_mount+0x2d/0x40 fs/fat/namei_vfat.c:1207
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x49/0x190 fs/super.c:1530
 do_new_mount+0x200/0x650 fs/namespace.c:3040
 path_mount+0x4ad/0xbb0 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3568
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff8708fd40 of 8 bytes by task 12844 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x10f/0x440 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x897/0xbd0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x51c/0xb50 kernel/printk/printk.c:2196
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2282
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2292
 _fat_msg+0xad/0xd1 fs/fat/misc.c:62
 fat_read_bpb fs/fat/inode.c:1488 [inline]
 fat_fill_super+0x140f/0x26c0 fs/fat/inode.c:1657
 vfat_fill_super+0x2c/0x40 fs/fat/namei_vfat.c:1200
 mount_bdev+0x1e2/0x280 fs/super.c:1400
 vfat_mount+0x2d/0x40 fs/fat/namei_vfat.c:1207
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x49/0x190 fs/super.c:1530
 do_new_mount+0x200/0x650 fs/namespace.c:3040
 path_mount+0x4ad/0xbb0 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3568
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000fffff2e9 -> 0x0000000100000374

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12844 Comm: syz-executor.3 Not tainted 6.0.0-rc5-syzkaller-00097-g38eddeedbbea-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
==================================================================
FAT-fs (loop3): Can't find a valid FAT filesystem
syz-executor.3 (12844) used greatest stack depth: 10992 bytes left