SELinux: memory leak in security_context_to_sid_core

Fix a bug and a philosophical decision about who handles errors.

security_context_to_sid_core() was leaking a context in the common case.
This was causing problems on fedora systems which recently have started
making extensive use of this function.

In discussion it was decided that if string_to_context_struct() had an
error it was its own responsibility to clean up any mess it created
along the way.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/ss/services.c

@@ -811,11 +811,12 @@ static int string_to_context_struct(struct policydb *pol,
 	/* Check the validity of the new context. */
 	if (!policydb_context_isvalid(pol, ctx)) {
 		rc = -EINVAL;
-		context_destroy(ctx);
 		goto out;
 	}
 	rc = 0;
 out:
+	if (rc)
+		context_destroy(ctx);
 	return rc;
 }
 
@@ -868,8 +869,7 @@ static int security_context_to_sid_core(const char *scontext, u32 scontext_len,
 	} else if (rc)
 		goto out;
 	rc = sidtab_context_to_sid(&sidtab, &context, sid);
-	if (rc)
-		context_destroy(&context);
+	context_destroy(&context);
 out:
 	read_unlock(&policy_rwlock);
 	kfree(scontext2);