linux-kernel - [PATCH 4.13 65/85] pkcs7: Prevent NULL pointer dereference, since sinfo is not always set.

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Date:   Tue, 24 Oct 2017 15:07:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Eric Sesterhenn <eric.sesterhenn@...-dsec.de>,
        David Howells <dhowells@...hat.com>
Subject: [PATCH 4.13 65/85] pkcs7: Prevent NULL pointer dereference, since sinfo is not always set.

4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Sesterhenn <eric.sesterhenn@...-dsec.de>

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@...-dsec.de>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 crypto/asymmetric_keys/pkcs7_parser.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -88,6 +88,9 @@ static int pkcs7_check_authattrs(struct
 	bool want = false;
 
 	sinfo = msg->signed_infos;
+	if (!sinfo)
+		goto inconsistent;
+
 	if (sinfo->authattrs) {
 		want = true;
 		msg->have_authattrs = true;