[moderation] [exfat?] KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 83a7eefedc9b Linux 6.10-rc3
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=150686de980000
kernel config: https://syzkaller.appspot.com/x/.config?x=68336ea4b6f4fc09
dashboard link: https://syzkaller.appspot.com/bug?extid=8bce3dd851b881dbbaa8
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [hiro...@mail.parknet.co.jp linki...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org sj155...@samsung.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/dc4448d7f810/disk-83a7eefe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1b7e727f29b/vmlinux-83a7eefe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/470dd9374113/bzImage-83a7eefe.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8bce3d...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 8192
==================================================================
BUG: KCSAN: data-race in mark_buffer_dirty_inode / sync_mapping_buffers

write to 0xffff888106ae7670 of 8 bytes by task 21540 on cpu 1:
__remove_assoc_queue fs/buffer.c:516 [inline]
fsync_buffers_list fs/buffer.c:791 [inline]
sync_mapping_buffers+0x162/0x7e0 fs/buffer.c:577
fat_file_fsync+0xad/0x100 fs/fat/file.c:195
vfs_fsync_range+0x122/0x140 fs/sync.c:188
generic_write_sync include/linux/fs.h:2794 [inline]
generic_file_write_iter+0x191/0x1d0 mm/filemap.c:4140
iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x3ab/0x960 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106ae7670 of 8 bytes by task 21534 on cpu 0:
mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:680
fat_mirror_bhs+0x241/0x330 fs/fat/fatent.c:398
fat_ent_write+0xcc/0xe0 fs/fat/fatent.c:423
fat_chain_add+0x15f/0x400 fs/fat/misc.c:136
fat_add_cluster fs/fat/inode.c:113 [inline]
__fat_get_block fs/fat/inode.c:155 [inline]
fat_get_block+0x46b/0x5e0 fs/fat/inode.c:190
__block_write_begin_int+0x417/0xfa0 fs/buffer.c:2128
__block_write_begin fs/buffer.c:2177 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2236
cont_write_begin+0x486/0x6b0 fs/buffer.c:2590
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
cont_expand_zero fs/buffer.c:2517 [inline]
cont_write_begin+0x186/0x6b0 fs/buffer.c:2580
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_cont_expand_simple+0xaa/0x150 fs/buffer.c:2481
fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
fat_setattr+0x2aa/0x840 fs/fat/file.c:513
notify_change+0x814/0x8a0 fs/attr.c:497
do_truncate fs/open.c:65 [inline]
do_ftruncate+0x3e1/0x470 fs/open.c:181
do_sys_ftruncate fs/open.c:199 [inline]
__do_sys_ftruncate fs/open.c:207 [inline]
__se_sys_ftruncate fs/open.c:205 [inline]
__x64_sys_ftruncate+0x6a/0xc0 fs/open.c:205
x64_sys_call+0x1f60/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:78
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888106b56670 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21534 Comm: syz-executor.0 Tainted: G W 6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================


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