Change DecryptSigBlock to return the parsed DigestInfo's length, so

the caller can check it. Patch by wtchang@redhat.com. r=nelson,rrelyea, a=schrep.
Bug 351848

1 files changed, 14 insertions, 6 deletions

diff --git a/security/nss/lib/cryptohi/secvfy.c b/security/nss/lib/cryptohi/secvfy.c
index 7310dfbbe..94a0b3563 100644
--- a/security/nss/lib/cryptohi/secvfy.c
+++ b/security/nss/lib/cryptohi/secvfy.c
@@ -54,10 +54,12 @@
 ** Decrypt signature block using public key
 ** Store the hash algorithm oid tag in *tagp
 ** Store the digest in the digest buffer
+** Store the digest length in *digestlen
 ** XXX this is assuming that the signature algorithm has WITH_RSA_ENCRYPTION
 */
 static SECStatus
-DecryptSigBlock(SECOidTag *tagp, unsigned char *digest, unsigned int len,
+DecryptSigBlock(SECOidTag *tagp, unsigned char *digest,
+		unsigned int *digestlen, unsigned int maxdigestlen,
 		SECKEYPublicKey *key, const SECItem *sig, char *wincx)
 {
     SGNDigestInfo *di   = NULL;
@@ -93,12 +95,13 @@ DecryptSigBlock(SECOidTag *tagp, unsigned char *digest, unsigned int len,
     if (di->digestAlgorithm.parameters.len > 2) {
 	goto sigloser;
     }
-    if (di->digest.len > len) {
+    if (di->digest.len > maxdigestlen) {
 	PORT_SetError(SEC_ERROR_OUTPUT_LEN);
 	goto loser;
     }
     PORT_Memcpy(digest, di->digest.data, di->digest.len);
     *tagp = tag;
+    *digestlen = di->digest.len;
     goto done;
 
   sigloser:
@@ -139,6 +142,7 @@ struct VFYContextStr {
 	/* the full ECDSA signature */
 	unsigned char ecdsasig[2 * MAX_ECKEY_LEN];
     } u;
+    unsigned int rsadigestlen;
     void * wincx;
     void *hashcx;
     const SECHashObject *hashobj;
@@ -336,9 +340,11 @@ vfy_CreateContextPrivate(const SECKEYPublicKey *key, const SECItem *sig,
 	    cx->key = SECKEY_CopyPublicKey((SECKEYPublicKey *)key); 
 	    if (sig) {
 		SECOidTag hashid = SEC_OID_UNKNOWN;
-	    	rv = DecryptSigBlock(&hashid, cx->u.buffer,
+		unsigned int digestlen = 0;
+	    	rv = DecryptSigBlock(&hashid, cx->u.buffer, &digestlen,
 			HASH_LENGTH_MAX, cx->key, sig, (char*)wincx);
 		cx->alg = hashid;
+		cx->rsadigestlen = digestlen;
 	    } else {
 		rv = decodeSigAlg(algid, params, key, &cx->alg);
 	    }
@@ -497,14 +503,15 @@ VFY_EndWithSignature(VFYContext *cx, SECItem *sig)
       case VFY_RSA:
 	if (sig) {
 	    SECOidTag hashid = SEC_OID_UNKNOWN;
-	    rv = DecryptSigBlock(&hashid, cx->u.buffer, 
+	    rv = DecryptSigBlock(&hashid, cx->u.buffer, &cx->rsadigestlen,
 		    HASH_LENGTH_MAX, cx->key, sig, (char*)cx->wincx);
 	    if ((rv != SECSuccess) || (hashid != cx->alg)) {
 		PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
 		return SECFailure;
 	    }
 	}
-	if (PORT_Memcmp(final, cx->u.buffer, part)) {
+	if ((part != cx->rsadigestlen) ||
+		PORT_Memcmp(final, cx->u.buffer, part)) {
 	    PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
 	    return SECFailure;
 	}
@@ -543,7 +550,8 @@ VFY_VerifyDigest(SECItem *digest, SECKEYPublicKey *key, SECItem *sig,
     if (cx != NULL) {
 	switch (key->keyType) {
 	case rsaKey:
-	    if (PORT_Memcmp(digest->data, cx->u.buffer, digest->len)) {
+	    if ((digest->len != cx->rsadigestlen) ||
+		PORT_Memcmp(digest->data, cx->u.buffer, digest->len)) {
 		PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
 	    } else {
 		rv = SECSuccess;