KCSAN: data-race in ext4_setattr / generic_file_buffered

KCSAN: data-race in ext4_setattr / generic_file_buffered_read (3)
Status: moderation: reported on 2020/12/07 11:45
Reported-by: syzbot+d3272ea1c7536cf44408@syzkaller.appspotmail.com
First crash: 71d, last: 11d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ext4_setattr / generic_file_buffered_read (2)				3	118d	133d	0/17	auto-closed as invalid on 2020/11/02 08:43
upstream	KCSAN: data-race in ext4_setattr / generic_file_buffered_read				16	170d	220d	0/17	auto-closed as invalid on 2020/09/11 12:48

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ext4_setattr / generic_file_buffered_read

write to 0xffff88810d98cb90 of 8 bytes by task 15988 on cpu 1:
 i_size_write include/linux/fs.h:870 [inline]
 ext4_setattr+0xe19/0xf60 fs/ext4/inode.c:5479
 notify_change+0x7b3/0xa50 fs/attr.c:336
 do_truncate+0xe0/0x120 fs/open.c:64
 handle_truncate fs/namei.c:2912 [inline]
 do_open fs/namei.c:3258 [inline]
 path_openat+0x1a37/0x20a0 fs/namei.c:3371
 do_filp_open+0xbd/0x1d0 fs/namei.c:3398
 do_sys_openat2+0xa3/0x240 fs/open.c:1172
 do_sys_open fs/open.c:1188 [inline]
 __do_sys_creat fs/open.c:1262 [inline]
 __se_sys_creat fs/open.c:1256 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1256
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810d98cb90 of 8 bytes by task 15982 on cpu 0:
 i_size_read include/linux/fs.h:848 [inline]
 generic_file_buffered_read+0x2a1/0x9a0 mm/filemap.c:2496
 generic_file_read_iter+0x80/0x3d0 mm/filemap.c:2633
 ext4_file_read_iter+0x2d0/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:788 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:867
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5db/0xca0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1312 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15982 Comm: syz-executor.0 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (10):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/14 02:02	upstream	65f0d241	269d24e8	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2021/01/11 16:22	upstream	7c53f6b6	2c1f2513	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/30 13:42	upstream	139711f0	ecb8c012	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/15 20:17	upstream	148842c9	f213e07e	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/13 22:34	upstream	ec6f5e0e	8f160dd5	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/28 03:01	upstream	c84e1efa	486f93ef	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/27 18:49	upstream	85a2c56c	486f93ef	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/21 09:52	upstream	27bba9c5	68068804	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/20 18:41	upstream	4d02da97	68068804	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/15 03:29	upstream	e28c0d7c	1bf9a662	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu