KCSAN: data-race in copy_page_to_iter / ext4_fill

KCSAN: data-race in copy_page_to_iter / ext4_fill_super
Status: auto-closed as invalid on 2021/07/31 12:41
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 178d, last: 115d

Sample crash report:

==================================================================
BUG: KCSAN: data-race in copy_page_to_iter / ext4_fill_super

write to 0xffff88813d13d40c of 4 bytes by task 12791 on cpu 1:
 ext4_free_blocks_count_set fs/ext4/ext4.h:3251 [inline]
 ext4_fill_super+0x68e0/0x8030 fs/ext4/super.c:5029
 mount_bdev+0x1e8/0x290 fs/super.c:1368
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6639
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1498
 do_new_mount fs/namespace.c:2905 [inline]
 path_mount+0x11d4/0x1ce0 fs/namespace.c:3235
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813d13d400 of 1024 bytes by task 12778 on cpu 0:
 instrument_copy_to_user include/linux/instrumented.h:119 [inline]
 copyout lib/iov_iter.c:189 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:261 [inline]
 copy_page_to_iter+0x320/0x860 lib/iov_iter.c:973
 filemap_read+0xf06/0x1230 mm/filemap.c:2605
 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2701
 blkdev_read_iter+0xb9/0xf0 fs/block_dev.c:1730
 call_read_iter include/linux/fs.h:2108 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x565/0x5d0 fs/read_write.c:496
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12778 Comm: systemd-udevd Not tainted 5.13.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/06/26 12:37	upstream	b7050b242430	9d2ab5df	.config	log	report	info	KCSAN: data-race in copy_page_to_iter / ext4_fill_super
ci2-upstream-kcsan-gce	2021/06/17 20:49	upstream	70585216fe77	aba2b2fb	.config	log	report	info	KCSAN: data-race in copy_page_to_iter / ext4_fill_super
ci2-upstream-kcsan-gce	2021/05/14 23:38	upstream	bd3c9cdb21a2	8bdd5343	.config	log	report	info	KCSAN: data-race in copy_page_to_iter / ext4_fill_super
ci2-upstream-kcsan-gce	2021/05/10 13:37	upstream	6efb943b8616	ca873091	.config	log	report	info	KCSAN: data-race in copy_page_to_iter / ext4_fill_super
ci2-upstream-kcsan-gce	2021/04/28 01:59	upstream	e359bce39d90	805b5003	.config	log	report	info	KCSAN: data-race in copy_page_to_iter / ext4_fill_super
ci2-upstream-kcsan-gce	2021/04/24 21:17	upstream	2a1d7946fa53	17f0b706	.config	log	report	info	KCSAN: data-race in copy_page_to_iter / ext4_fill_super