add some sanity checks

Author: sjaeckel

src/pk/ecc/ecc_sign_hash_internal.c

@@ -48,6 +48,10 @@ int ecc_sign_hash_internal(const unsigned char *in,  unsigned long inlen,
       if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, pbytes)) != CRYPT_OK)   { goto errnokey; }
    }
    else {
+      if (pbytes >= MAXBLOCKSIZE) {
+         err = CRYPT_BUFFER_OVERFLOW;
+         goto error;
+      }
       shift_right = 8 - pbits % 8;
       for (i=0, ch=0; i<pbytes; i++) {
         buf[i] = ch;

src/pk/ecc/ecc_verify_hash_internal.c

@@ -69,6 +69,10 @@ int ecc_verify_hash_internal(void *r, void *s,
       if ((err = mp_read_unsigned_bin(e, (unsigned char *)hash, pbytes)) != CRYPT_OK)                   { goto error; }
    }
    else {
+      if (pbytes >= MAXBLOCKSIZE) {
+         err = CRYPT_BUFFER_OVERFLOW;
+         goto error;
+      }
       shift_right = 8 - pbits % 8;
       for (i=0, ch=0; i<pbytes; i++) {
         buf[i] = ch;

src/pk/ecc/ecc_verify_hash_rfc5656.c

@@ -49,6 +49,11 @@ int ecc_verify_hash_rfc5656(const unsigned char *sig,  unsigned long siglen,
                                         LTC_SSHDATA_MPINT,  s,
                                         LTC_SSHDATA_EOL,    NULL)) != CRYPT_OK) goto error;
 
+   if (slen != siglen) {
+      err = CRYPT_INVALID_PACKET;
+      goto error;
+   }
+
    /* Check curve matches identifier string */
    if ((err = ecc_ssh_ecdsa_encode_name(name2, &name2len, key)) != CRYPT_OK) goto error;
    if (XSTRCMP(name,name2) != 0) {