syzbot found at least one path leads to an ip_mr_output()
without RCU being held.
Add guard(rcu)() to fix this in a concise way.
WARNING: net/ipv6/ip6mr.c:2376 at ip6_mr_output+0xe0b/0x1040 net/ipv6/ip6mr.c:2376, CPU#1: kworker/1:2/121
Call Trace:
ip6tunnel_xmit include/net/ip6_tunnel.h:162 [inline]
udp_tunnel6_xmit_skb+0x640/0xad0 net/ipv6/ip6_udp_tunnel.c:112
send6+0x5ac/0x8d0 drivers/net/wireguard/socket.c:152
wg_socket_send_skb_to_peer+0x111/0x1d0 drivers/net/wireguard/socket.c:178
wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
wg_packet_tx_worker+0x1c8/0x7c0 drivers/net/wireguard/send.c:276
process_one_work kernel/workqueue.c:3239 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3322
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Fixes: 96e8f5a9fe2d ("net: ipv6: Add ip6_mr_output()")
Reported-by: syzbot+0141c834e47059395621@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/685e86b3.a00a0220.129264.0003.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet
Cc: Petr Machata
Cc: Roopa Prabhu
Cc: Nikolay Aleksandrov
Cc: Benjamin Poirier
Cc: Ido Schimmel
---
net/ipv6/ip6mr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index a35f4f1c658960e4b087848461f3ea7af653d070..eb6a00262510f1cd6a9d48fab80bdd0d496bb7ee 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -2373,7 +2373,7 @@ int ip6_mr_output(struct net *net, struct sock *sk, struct sk_buff *skb)
int err;
int vif;
- WARN_ON_ONCE(!rcu_read_lock_held());
+ guard(rcu)();
if (IP6CB(skb)->flags & IP6SKB_FORWARDED)
goto ip6_output;
--
2.50.0.727.gbf7dc18ff4-goog