Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2017-11-28' into staging

nbd patches for 2017-11-28

Eric Blake - 0/2 fix two NBD server CVEs

# gpg: Signature made Tue 28 Nov 2017 12:58:29 GMT
# gpg:                using RSA key 0xA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>"
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>"
# gpg:                 aka "[jpeg image of size 6874]"
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2017-11-28:
  nbd/server: CVE-2017-15118 Stack smash on large export name
  nbd/server: CVE-2017-15119 Reject options larger than 32M
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

nbd/server.c

@@ -386,6 +386,10 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length,
         msg = "name length is incorrect";
         goto invalid;
     }
+    if (namelen >= sizeof(name)) {
+        msg = "name too long for qemu";
+        goto invalid;
+    }
     if (nbd_read(client->ioc, name, namelen, errp) < 0) {
         return -EIO;
     }
@@ -673,6 +677,12 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
         }
         length = be32_to_cpu(length);
 
+        if (length > NBD_MAX_BUFFER_SIZE) {
+            error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
+                       length, NBD_MAX_BUFFER_SIZE);
+            return -EINVAL;
+        }
+
         trace_nbd_negotiate_options_check_option(option,
                                                  nbd_opt_lookup(option));
         if (client->tlscreds &&