pkcs7: Prevent NULL pointer dereference, since sinfo is not always set.

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>
cc: stable@vger.kernel.org # 4.3+

diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index af4cd864911752478ba5f3c2732273f9624d434f..d140d8bb2c96140c408b1e3450f288e562372743 100644 (file)
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -88,6 +88,9 @@ static int pkcs7_check_authattrs(struct pkcs7_message *msg)
        bool want = false;
 
        sinfo = msg->signed_infos;
+       if (!sinfo)
+               goto inconsistent;
+
        if (sinfo->authattrs) {
                want = true;
                msg->have_authattrs = true;