diff mbox series

[7/7] xfrm: fix a data-race in xfrm_lookup_with_ifid()

Message ID 20231017083723.1364940-8-steffen.klassert@secunet.com (mailing list archive)
State Accepted
Commit de5724ca38fd5e442bae9c1fab31942b6544012d
Delegated to: Netdev Maintainers
Headers show
Series [1/7] net: xfrm: skip policies marked as dead while reinserting policies | expand

Checks

Context Check Description
netdev/series_format warning Pull request is its own cover letter; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1372 this patch: 1372
netdev/cc_maintainers fail 2 blamed authors not CCed: arnd@arndb.de edumazet@google.com; 3 maintainers not CCed: pabeni@redhat.com arnd@arndb.de edumazet@google.com
netdev/build_clang success Errors and warnings before: 1386 this patch: 1386
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1397 this patch: 1397
netdev/checkpatch warning WARNING: Possible repeated word: 'Google'
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Steffen Klassert Oct. 17, 2023, 8:37 a.m. UTC 
From: Eric Dumazet <edumazet@google.com>

syzbot complains about a race in xfrm_lookup_with_ifid() [1]

When preparing commit 0a9e5794b21e ("xfrm: annotate data-race
around use_time") I thought xfrm_lookup_with_ifid() was modifying
a still private structure.

[1]
BUG: KCSAN: data-race in xfrm_lookup_with_ifid / xfrm_lookup_with_ifid

write to 0xffff88813ea41108 of 8 bytes by task 8150 on cpu 1:
xfrm_lookup_with_ifid+0xce7/0x12d0 net/xfrm/xfrm_policy.c:3218
xfrm_lookup net/xfrm/xfrm_policy.c:3270 [inline]
xfrm_lookup_route+0x3b/0x100 net/xfrm/xfrm_policy.c:3281
ip6_dst_lookup_flow+0x98/0xc0 net/ipv6/ip6_output.c:1246
send6+0x241/0x3c0 drivers/net/wireguard/socket.c:139
wg_socket_send_skb_to_peer+0xbd/0x130 drivers/net/wireguard/socket.c:178
wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

write to 0xffff88813ea41108 of 8 bytes by task 15867 on cpu 0:
xfrm_lookup_with_ifid+0xce7/0x12d0 net/xfrm/xfrm_policy.c:3218
xfrm_lookup net/xfrm/xfrm_policy.c:3270 [inline]
xfrm_lookup_route+0x3b/0x100 net/xfrm/xfrm_policy.c:3281
ip6_dst_lookup_flow+0x98/0xc0 net/ipv6/ip6_output.c:1246
send6+0x241/0x3c0 drivers/net/wireguard/socket.c:139
wg_socket_send_skb_to_peer+0xbd/0x130 drivers/net/wireguard/socket.c:178
wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x00000000651cd9d1 -> 0x00000000651cd9d2

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15867 Comm: kworker/u4:58 Not tainted 6.6.0-rc4-syzkaller-00016-g5e62ed3b1c8a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker

Fixes: 0a9e5794b21e ("xfrm: annotate data-race around use_time")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_policy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 99df2862bdc9..d24b4d4f620e 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3220,7 +3220,7 @@  struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
 	}
 
 	for (i = 0; i < num_pols; i++)
-		pols[i]->curlft.use_time = ktime_get_real_seconds();
+		WRITE_ONCE(pols[i]->curlft.use_time, ktime_get_real_seconds());
 
 	if (num_xfrms < 0) {
 		/* Prohibit the flow */