KCSAN: data-race in dst_cache_set_ip6 / fib6_clean

KCSAN: data-race in dst_cache_set_ip6 / fib6_clean_node (2)
Status: auto-closed as invalid on 2021/01/02 02:50
Reported-by: syzbot+c3051d12e7037c8dd4d3@syzkaller.appspotmail.com
First crash: 318d, last: 242d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in dst_cache_set_ip6 / fib6_clean_node	3	356d	394d	0/22	auto-closed as invalid on 2020/09/10 11:48
upstream	KCSAN: data-race in dst_cache_set_ip6 / fib6_clean_node (3)	5	164d	193d	0/22	auto-closed as invalid on 2021/03/21 16:17
upstream	KCSAN: data-race in dst_cache_set_ip6 / fib6_clean_node (4)	4	105d	121d	0/22	auto-closed as invalid on 2021/05/19 03:13

Sample crash report:

==================================================================
BUG: KCSAN: data-race in dst_cache_set_ip6 / fib6_clean_node

write to 0xffff8880119a68ac of 4 bytes by task 7 on cpu 0:
 fib6_clean_node+0xc0/0x260 net/ipv6/ip6_fib.c:2177
 fib6_walk_continue+0x38e/0x430 net/ipv6/ip6_fib.c:2111
 fib6_walk net/ipv6/ip6_fib.c:2159 [inline]
 fib6_clean_tree net/ipv6/ip6_fib.c:2239 [inline]
 __fib6_clean_all+0x188/0x2b0 net/ipv6/ip6_fib.c:2255
 fib6_flush_trees+0x6c/0x80 net/ipv6/ip6_fib.c:2280
 rt_genid_bump_ipv6 include/net/net_namespace.h:458 [inline]
 addrconf_dad_completed+0x57f/0x860 net/ipv6/addrconf.c:4205
 addrconf_dad_work+0x8dd/0x1150 net/ipv6/addrconf.c:3958
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff8880119a68ac of 4 bytes by task 3130 on cpu 1:
 fib6_get_cookie_safe include/net/ip6_fib.h:283 [inline]
 rt6_get_cookie include/net/ip6_fib.h:304 [inline]
 dst_cache_set_ip6+0xab/0x1b0 net/core/dst_cache.c:115
 send6+0x256/0x3a0 drivers/net/wireguard/socket.c:148
 wg_socket_send_skb_to_peer+0xbb/0x120 drivers/net/wireguard/socket.c:177
 wg_packet_create_data_done drivers/net/wireguard/send.c:252 [inline]
 wg_packet_tx_worker+0x1e3/0x4c0 drivers/net/wireguard/send.c:280
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3130 Comm: kworker/1:2 Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: wg-crypt-wg0 wg_packet_tx_worker
==================================================================

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info
ci2-upstream-kcsan-gce	2020/11/28 02:49	upstream	c84e1efae022	486f93ef	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/30 05:35	upstream	23859ae44402	a0c7169a	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/23 11:44	upstream	f9893351acae	4e740c00	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/17 05:15	upstream	54a4c789ca80	6e262c73	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/19 04:47	upstream	92ab97adeefc	53ce8104	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/13 11:37	upstream	ef2e9a563b0c	455eff3c	.config	log	report