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

[Debin Zhu <mowenroot@163.com>]

Added IPv6 socket checks in `calipso_sock_getattr`, `calipso_sock_setattr`,
and `calipso_sock_delattr` functions.
Return `-EAFNOSUPPORT` error code if the socket is not of the IPv6 type.
This fix prevents the IPv6 datagram code from 
incorrectly calling the IPv4 datagram code,
thereby avoiding a NULL pointer exception.

Signed-off-by: Debin Zhu <mowenroot@163.com>
Signed-off-by: Bitao Ouyang <1985755126@qq.com>
---
 net/ipv6/calipso.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/net/ipv6/calipso.c b/net/ipv6/calipso.c
index dbcea9fee..ef55e4176 100644
--- a/net/ipv6/calipso.c
+++ b/net/ipv6/calipso.c
@@ -1072,8 +1072,13 @@ static int calipso_sock_getattr(struct sock *sk,
 	struct ipv6_opt_hdr *hop;
 	int opt_len, len, ret_val = -ENOMSG, offset;
 	unsigned char *opt;
-	struct ipv6_txoptions *txopts = txopt_get(inet6_sk(sk));
-
+	struct ipv6_pinfo *pinfo = inet6_sk(sk);
+	struct ipv6_txoptions *txopts;
+	/* Prevent IPv6 datagram code from calling IPv4 datagram code, causing pinet6 to be NULL  */
+	if (!pinfo)
+		return -EAFNOSUPPORT;
+
+	txopts = txopt_get(pinfo);
 	if (!txopts || !txopts->hopopt)
 		goto done;

@@ -1125,8 +1130,13 @@ static int calipso_sock_setattr(struct sock *sk,
 {
 	int ret_val;
 	struct ipv6_opt_hdr *old, *new;
-	struct ipv6_txoptions *txopts = txopt_get(inet6_sk(sk));
-
+	struct ipv6_pinfo *pinfo = inet6_sk(sk);
+	struct ipv6_txoptions *txopts;
+	/* Prevent IPv6 datagram code from calling IPv4 datagram code, causing pinet6 to be NULL  */
+	if (!pinfo)
+		return -EAFNOSUPPORT;
+
+	txopts = txopt_get(pinfo);
 	old = NULL;
 	if (txopts)
 		old = txopts->hopopt;
@@ -1153,8 +1163,13 @@ static int calipso_sock_setattr(struct sock *sk,
 static void calipso_sock_delattr(struct sock *sk)
 {
 	struct ipv6_opt_hdr *new_hop;
-	struct ipv6_txoptions *txopts = txopt_get(inet6_sk(sk));
-
+	struct ipv6_pinfo *pinfo = inet6_sk(sk);
+	struct ipv6_txoptions *txopts;
+	/* Prevent IPv6 datagram code from calling IPv4 datagram code, causing pinet6 to be NULL  */
+	if (!pinfo)
+		return -EAFNOSUPPORT;
+
+	txopts = txopt_get(pinfo);
 	if (!txopts || !txopts->hopopt)
 		goto done;

--
2.34.1