netlabel: Fix NULL pointer exception caused by CALIPSO on IPv4 sockets

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: netlabel: Fix NULL pointer exception caused by CALIPSO on IPv4 sockets When calling netlbl_conn_setattr(), addr->sa_family is used to determine the function behavior. If sk is an IPv4 socket, but the connect function is called with an IPv6 address, the function calipso_sock_setattr() is triggered. Inside this function, the following code is executed: sk_fullsock(__sk) ? inet_sk(__sk)->pinet6 : NULL; Since sk is an IPv4 socket, pinet6 is NULL, leading to a null pointer dereference. This patch fixes the issue by checking if inet6_sk(sk) returns a NULL pointer before accessing pinet6.

References

• https://git.kernel.org/stable/c/1ad9166cab6a0f5c0b10344a97bdf749ae11dcbf
• https://git.kernel.org/stable/c/1e38f7a6cdd68377f8a4189b2fbaec14a6dd5152
• https://git.kernel.org/stable/c/a7e89541d05b98c79a51c0f95df020f8e82b62ed
• https://git.kernel.org/stable/c/797e5371cf55463b4530bab3fef5f27f7c6657a8
• https://git.kernel.org/stable/c/1927d0bcd5b81e80971bf6b8eba267508bd1c78b
• https://git.kernel.org/stable/c/3ba9cf69de50e8abed32b448616c313baa4c5712
• https://git.kernel.org/stable/c/9fe3839588db7519030377b7dee3f165e654f6c5
• https://git.kernel.org/stable/c/172a8a996a337206970467e871dd995ac07640b1
• https://git.kernel.org/stable/c/078aabd567de3d63d37d7673f714e309d369e6e2