[PATCH v3 0/2] resolve gtp possible deadlock warning

[PATCH v3 0/2] resolve gtp possible deadlock warning

[Daniel Yang]

Fixes deadlock described in this bug:
https://syzkaller.appspot.com/bug?extid=e953a8f3071f5c0a28fd.
Specific crash report here:
https://syzkaller.appspot.com/text?tag=CrashReport&x=14670e07980000.

This bug is a false positive lockdep warning since gtp and smc use
completely different socket protocols.

Lockdep thinks that lock_sock() in smc will deadlock with gtp's
lock_sock() acquisition.

Adding lockdep annotations on smc socket creation prevents these false
positives.

Daniel Yang (2):
  Patch from D. Wythe <alibuda@linux.alibaba.com>
  Move lockdep annotation to separate function for readability.

 net/smc/smc_inet.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

-- 
2.39.2

[PATCH v3 1/2] Patch from

[Daniel Yang]

From: D. Wythe <alibuda@linux.alibaba.com>

Adds lockdep annotations on smc inet socket creation

Tested-by: Daniel Yang <danielyangkang@gmail.com>
Signed-off-by: Daniel Yang <danielyangkang@gmail.com>
Reported-by: syzbot+e953a8f3071f5c0a28fd@syzkaller.appspotmail.com
---
 net/smc/smc_inet.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/net/smc/smc_inet.c b/net/smc/smc_inet.c
index a5b204160..7ae49ffd2 100644
--- a/net/smc/smc_inet.c
+++ b/net/smc/smc_inet.c
@@ -108,14 +108,39 @@ static struct inet_protosw smc_inet6_protosw = {
 };
 #endif /* CONFIG_IPV6 */
 
+static struct lock_class_key smc_slock_keys[2];
+static struct lock_class_key smc_keys[2];
+
 static int smc_inet_init_sock(struct sock *sk)
 {
 	struct net *net = sock_net(sk);
+	int rc;
 
 	/* init common smc sock */
 	smc_sk_init(net, sk, IPPROTO_SMC);
 	/* create clcsock */
-	return smc_create_clcsk(net, sk, sk->sk_family);
+	rc = smc_create_clcsk(net, sk, sk->sk_family);
+	if (rc)
+		return rc;
+
+	switch (sk->sk_family) {
+	case AF_INET:
+		sock_lock_init_class_and_name(sk, "slock-AF_INET-SMC",
+					      &smc_slock_keys[0],
+				"sk_lock-AF_INET-SMC",
+				&smc_keys[0]);
+		break;
+	case AF_INET6:
+		sock_lock_init_class_and_name(sk, "slock-AF_INET6-SMC",
+					      &smc_slock_keys[1],
+				"sk_lock-AF_INET6-SMC",
+				&smc_keys[1]);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return 0;
 }
 
 int __init smc_inet_init(void)
-- 
2.39.2

[PATCH v3 2/2] Move lockdep annotation to separate function for readability.

[Daniel Yang]

From: Daniel Yang <danielyangkang@gmail.com>

Moved lockdep annotation to separate function for readability.

Signed-off-by: Daniel Yang <danielyangkang@gmail.com>
Reported-by: syzbot+e953a8f3071f5c0a28fd@syzkaller.appspotmail.com
---
 net/smc/smc_inet.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/net/smc/smc_inet.c b/net/smc/smc_inet.c
index 7ae49ffd2..b3eedc3b0 100644
--- a/net/smc/smc_inet.c
+++ b/net/smc/smc_inet.c
@@ -111,18 +111,7 @@ static struct inet_protosw smc_inet6_protosw = {
 static struct lock_class_key smc_slock_keys[2];
 static struct lock_class_key smc_keys[2];
 
-static int smc_inet_init_sock(struct sock *sk)
-{
-	struct net *net = sock_net(sk);
-	int rc;
-
-	/* init common smc sock */
-	smc_sk_init(net, sk, IPPROTO_SMC);
-	/* create clcsock */
-	rc = smc_create_clcsk(net, sk, sk->sk_family);
-	if (rc)
-		return rc;
-
+static inline void smc_inet_lockdep_annotate(struct sock *sk)
+{
 	switch (sk->sk_family) {
 		case AF_INET:
 			sock_lock_init_class_and_name(sk, "slock-AF_INET-SMC",
@@ -139,8 +128,21 @@ static int smc_inet_init_sock(struct sock *sk)
 		default:
 			WARN_ON_ONCE(1);
 	}
+}
 
-	return 0;
+static int smc_inet_init_sock(struct sock *sk)
+{
+	struct net *net = sock_net(sk);
+	int rc;
+
+	/* init common smc sock */
+	smc_sk_init(net, sk, IPPROTO_SMC);
+	/* create clcsock */
+	rc = smc_create_clcsk(net, sk, sk->sk_family);
+	if (!rc)
+		smc_inet_lockdep_annotate(sk);
+
+	return rc;
 }
 
 int __init smc_inet_init(void)
-- 
2.39.2

Re: [PATCH v3 0/2] resolve gtp possible deadlock warning

[Jakub Kicinski]

On Mon, 14 Oct 2024 00:30:36 -0700 Daniel Yang wrote:
> Fixes deadlock described in this bug:
> https://syzkaller.appspot.com/bug?extid=e953a8f3071f5c0a28fd.
> Specific crash report here:
> https://syzkaller.appspot.com/text?tag=CrashReport&x=14670e07980000.
> 
> This bug is a false positive lockdep warning since gtp and smc use
> completely different socket protocols.
> 
> Lockdep thinks that lock_sock() in smc will deadlock with gtp's
> lock_sock() acquisition.
> 
> Adding lockdep annotations on smc socket creation prevents these false
> positives.

This posting looks corrupted, please fix and repost, if it's 
not accidental.