From: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Date: Wed, 12 Sep 2012 10:26:55 +0000 (+0300)
Subject: digsig: add hash size comparision on signature verification
X-Git-Tag: v3.5.5~175
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=df4d11d1581f21352b2a727c2a62ede4f0aa48b7;p=karo-tx-linux.git

digsig: add hash size comparision on signature verification

commit bc01637a80f5b670bd70a0279d3f93fa8de1c96d upstream.

When pkcs_1_v1_5_decode_emsa() returns without error and hash sizes do
not match, hash comparision is not done and digsig_verify_rsa() returns
no error.  This is a bug and this patch fixes it.

The bug was introduced in v3.3 by commit b35e286a640f ("lib/digsig:
pkcs_1_v1_5_decode_emsa cleanup").

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/lib/digsig.c b/lib/digsig.c
index 286d558033e2..8c0e62975c88 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -163,9 +163,11 @@ static int digsig_verify_rsa(struct key *key,
 	memcpy(out1 + head, p, l);
 
 	err = pkcs_1_v1_5_decode_emsa(out1, len, mblen, out2, &len);
+	if (err)
+		goto err;
 
-	if (!err && len == hlen)
-		err = memcmp(out2, h, hlen);
+	if (len != hlen || memcmp(out2, h, hlen))
+		err = -EINVAL;
 
 err:
 	mpi_free(in);