KCSAN: data-race in binder_dec_node_nilocked / binder_state

KCSAN: data-race in binder_dec_node_nilocked / binder_state_show (2)
Status: closed as invalid on 2020/06/18 14:24
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 501d, last: 466d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in binder_dec_node_nilocked / binder_state_show				1	594d	535d	0/22	auto-closed as invalid on 2020/04/17 15:24
upstream	KCSAN: data-race in binder_dec_node_nilocked / binder_state_show (3)				1	456d	456d	0/22	auto-closed as invalid on 2020/07/26 15:33

Sample crash report:

==================================================================
BUG: KCSAN: data-race in binder_dec_node_nilocked / binder_state_show

write to 0xffff88811cbf1b54 of 4 bytes by task 30681 on cpu 0:
 binder_state_show+0xd5/0x250 drivers/android/binder.c:5949
 seq_read+0x2ef/0x940 fs/seq_file.c:206
 full_proxy_read+0xb6/0xf0 fs/debugfs/file.c:229
 do_loop_readv_writev fs/read_write.c:715 [inline]
 do_loop_readv_writev fs/read_write.c:702 [inline]
 do_iter_read+0x33f/0x3a0 fs/read_write.c:936
 vfs_readv+0x9c/0xf0 fs/read_write.c:1054
 do_preadv+0x129/0x1c0 fs/read_write.c:1146
 __do_sys_preadv fs/read_write.c:1196 [inline]
 __se_sys_preadv fs/read_write.c:1191 [inline]
 __x64_sys_preadv+0x5e/0x80 fs/read_write.c:1191
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811cbf1b54 of 4 bytes by task 30674 on cpu 1:
 binder_dec_node_nilocked+0x34d/0x5d0 drivers/android/binder.c:1261
 binder_dec_node_tmpref+0x97/0x120 drivers/android/binder.c:1379
 binder_put_node drivers/android/binder.c:1387 [inline]
 binder_state_show+0x1a3/0x250 drivers/android/binder.c:5961
 seq_read+0x2ef/0x940 fs/seq_file.c:206
 full_proxy_read+0xb6/0xf0 fs/debugfs/file.c:229
 do_loop_readv_writev fs/read_write.c:715 [inline]
 do_loop_readv_writev fs/read_write.c:702 [inline]
 do_iter_read+0x33f/0x3a0 fs/read_write.c:936
 vfs_readv+0x9c/0xf0 fs/read_write.c:1054
 do_preadv+0x129/0x1c0 fs/read_write.c:1146
 __do_sys_preadv fs/read_write.c:1196 [inline]
 __se_sys_preadv fs/read_write.c:1191 [inline]
 __x64_sys_preadv+0x5e/0x80 fs/read_write.c:1191
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 30674 Comm: syz-executor.3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-upstream-kcsan-gce	2020/06/11 01:52	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	3ab7a05a	.config	log	report
ci2-upstream-kcsan-gce	2020/05/20 16:08	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	4afdfa20	.config	log	report
ci2-upstream-kcsan-gce	2020/05/07 08:08	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	4618eb2d	.config	log	report