[PATCH 4.4 24/27] pkcs7: Prevent NULL pointer dereference, since sinfo is not always set.

[Greg Kroah-Hartman]

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

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

From: Eric Sesterhenn <eric.sesterh...@x41-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.sesterh...@x41-dsec.de>
Signed-off-by: David Howells <dhowe...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.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
@@ -90,6 +90,9 @@ static int pkcs7_check_authattrs(struct
        bool want;
 
        sinfo = msg->signed_infos;
+       if (!sinfo)
+               goto inconsistent;
+
        if (sinfo->authattrs) {
                want = true;
                msg->have_authattrs = true;