[Linux-kernel-mentees] [PATCH] tcp: ipv4: Pass lockdep expression to RCU lists

Amol Grover frextrite at gmail.com
Fri Feb 21 17:57:14 UTC 2020


md5sig->head maybe traversed using hlist_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of socket lock.

Hence, add corresponding lockdep expression to silence false-positive
warnings, and harden RCU lists.

Signed-off-by: Amol Grover <frextrite at gmail.com>
---
 net/ipv4/tcp_ipv4.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1c7326e04f9b..6519429f32cd 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1000,7 +1000,8 @@ struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk,
 	if (!md5sig)
 		return NULL;
 
-	hlist_for_each_entry_rcu(key, &md5sig->head, node) {
+	hlist_for_each_entry_rcu(key, &md5sig->head, node,
+				 lockdep_sock_is_held(sk)) {
 		if (key->family != family)
 			continue;
 
@@ -1043,7 +1044,8 @@ static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk,
 	if (family == AF_INET6)
 		size = sizeof(struct in6_addr);
 #endif
-	hlist_for_each_entry_rcu(key, &md5sig->head, node) {
+	hlist_for_each_entry_rcu(key, &md5sig->head, node,
+				 lockdep_sock_is_held(sk)) {
 		if (key->family != family)
 			continue;
 		if (!memcmp(&key->addr, addr, size) &&
-- 
2.24.1



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