NetLabel: better error handling involving mls_export_cat()

Upon inspection it looked like the error handling for mls_export_cat() was
rather poor.  This patch addresses this by NULL'ing out kfree()'d pointers
before returning and checking the return value of the function everywhere
it is called.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 10 insertions, 8 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 18274b005090..b1f6fb36c699 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2399,31 +2399,33 @@ static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
         if (!ss_initialized)
                 return 0;
 
+        netlbl_secattr_init(&secattr);
+
         POLICY_RDLOCK;
 
         ctx = sidtab_search(&sidtab, sid);
         if (ctx == NULL)
                 goto netlbl_socket_setsid_return;
 
-        netlbl_secattr_init(&secattr);
         secattr.domain = kstrdup(policydb.p_type_val_to_name[ctx->type - 1],
                                  GFP_ATOMIC);
         mls_export_lvl(ctx, &secattr.mls_lvl, NULL);
         secattr.mls_lvl_vld = 1;
-        mls_export_cat(ctx,
-                       &secattr.mls_cat,
-                       &secattr.mls_cat_len,
-                       NULL,
-                       NULL);
+        rc = mls_export_cat(ctx,
+                            &secattr.mls_cat,
+                            &secattr.mls_cat_len,
+                            NULL,
+                            NULL);
+        if (rc != 0)
+                goto netlbl_socket_setsid_return;
 
         rc = netlbl_socket_setattr(sock, &secattr);
         if (rc == 0)
                 sksec->nlbl_state = NLBL_LABELED;
 
-        netlbl_secattr_destroy(&secattr);
-
 netlbl_socket_setsid_return:
         POLICY_RDUNLOCK;
+        netlbl_secattr_destroy(&secattr);
         return rc;
 }