[PATCH] selinux: Read sk->sk_family once in selinux_socket_bind()

[Mikhail Ivanov]

selinux_socket_bind() is called without holding the socket lock.

Use READ_ONCE() to safely read sk->sk_family for IPv6 socket in case
of lockless transformation to IPv4 socket via IPV6_ADDRFORM [1].

[1] https://lore.kernel.org/all/20240202095404.183274-1-edumazet@google.com/

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
---
 security/selinux/hooks.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 5e5f3398f39d..b7adff2cf5f6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4715,8 +4715,10 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
 	if (err)
 		goto out;
 
+	/* IPV6_ADDRFORM can change sk->sk_family under us. */
+	family = READ_ONCE(sk->sk_family);
+
 	/* If PF_INET or PF_INET6, check name_bind permission for the port. */
-	family = sk->sk_family;
 	if (family == PF_INET || family == PF_INET6) {
 		char *addrp;
 		struct common_audit_data ad;

base-commit: 034294fbfdf0ded4f931f9503d2ca5bbf8b9aebd
-- 
2.34.1