2020-02-21 17:58:19

by Amol Grover

Subject: [PATCH] tcp: ipv4: Pass lockdep expression to RCU lists

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 <[email protected]>
---
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

2020-02-24 21:07:40

by David Miller

Subject: Re: [PATCH] tcp: ipv4: Pass lockdep expression to RCU lists

From: Amol Grover <[email protected]>
Date: Fri, 21 Feb 2020 23:27:14 +0530

> 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 <[email protected]>

Applied.