From 6f0dee7d9c9b815c45b96cad2ab2958b4afe5840 Mon Sep 17 00:00:00 2001
From: Eric Sesterhenn <eric.sesterhenn@x41-dsec.de>
Date: Sun, 8 Oct 2017 20:02:32 +0200
Subject: [PATCH] pkcs7: Prevent NULL pointer dereference, since sinfo is not
 always set.

commit 68a1fdbbf8bd3378325e45c19e167a165f9ffc3a upstream.

The ASN.1 parser does not necessarily set the sinfo field,
this patch prevents a NULL pointer dereference on broken
input.

Fixes: 99db44350672 ("PKCS#7: Appropriately restrict authenticated attributes and content type")
Signed-off-by: Eric Sesterhenn <eric.sesterhenn@x41-dsec.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 crypto/asymmetric_keys/pkcs7_parser.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index 8f3056cd0399..2516e97c58f1 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -90,6 +90,9 @@ static int pkcs7_check_authattrs(struct pkcs7_message *msg)
 	bool want;
 
 	sinfo = msg->signed_infos;
+	if (!sinfo)
+		goto inconsistent;
+
 	if (sinfo->authattrs) {
 		want = true;
 		msg->have_authattrs = true;