From f3986c24728f03a346a10388fd6c15ea9ae16d41 Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Tue, 9 Oct 2018 18:16:11 +0200
Subject: [PATCH] steam-ihs: fix memleak on exception

When protobuf_dissect_unknown_field throws an exception,
steamdiscover_dissect_body_status will leak memory as
wmem_destroy_allocator is not called. Capture fuzz-2018-10-06-3104.pcap
from the linked bug leaks 64kiB memory in each frame 14 and 36.

Bug: 15171
Change-Id: I930d0738fde61799ab4ef2310f8ff11c1bcb032b
Fixes: v2.5.1rc0-130-g7ae954c7ac ("steam-ihs: Add dissector for the Steam IHS Discovery Protocol")
Reviewed-on: https://code.wireshark.org/review/30098
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>
---
 epan/dissectors/packet-steam-ihs-discovery.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/epan/dissectors/packet-steam-ihs-discovery.c b/epan/dissectors/packet-steam-ihs-discovery.c
index 1bec81e..9d238f4 100644
--- a/epan/dissectors/packet-steam-ihs-discovery.c
+++ b/epan/dissectors/packet-steam-ihs-discovery.c
@@ -491,9 +491,7 @@ steamdiscover_dissect_body_status(tvbuff_t *tvb, packet_info *pinfo, proto_tree
     protobuf_desc_t pb = { tvb, offset, bytes_left };
     protobuf_desc_t pb2 = { tvb, 0, 0 };
     protobuf_tag_t tag = { 0, 0, 0 };
-    wmem_allocator_t* strpool;
     guint8 *hostname;
-    strpool = wmem_allocator_new(WMEM_ALLOCATOR_SIMPLE);
     nstime_t timestamp;
     proto_tree *user_tree;
     proto_item *user_it;
@@ -522,7 +520,7 @@ steamdiscover_dissect_body_status(tvbuff_t *tvb, packet_info *pinfo, proto_tree
                 value = get_varint64(pb.tvb, pb.offset, pb.bytes_left, &len);
                 proto_tree_add_item(tree, hf_steam_ihs_discovery_body_status_hostname, pb.tvb,
                         pb.offset+len, (gint)value, ENC_UTF_8|ENC_NA);
-                hostname = tvb_get_string_enc(strpool, pb.tvb, pb.offset+len, (gint)value, ENC_UTF_8);
+                hostname = tvb_get_string_enc(wmem_packet_scope(), pb.tvb, pb.offset+len, (gint)value, ENC_UTF_8);
                 if(hostname && strlen(hostname)) {
                     col_add_fstr(pinfo->cinfo, COL_INFO, "%s from %s", hf_steam_ihs_discovery_header_msgtype_strings[STEAMDISCOVER_MSGTYPE_CLIENTBROADCASTMSGSTATUS].strptr, hostname);
                 }
@@ -615,7 +613,6 @@ steamdiscover_dissect_body_status(tvbuff_t *tvb, packet_info *pinfo, proto_tree
         }
         protobuf_seek_forward(&pb, len);
     }
-    wmem_destroy_allocator(strpool);
 }
 
 /* Dissect a CMsgRemoteDeviceAuthorizationRequest protobuf message body.
@@ -648,8 +645,6 @@ steamdiscover_dissect_body_authrequest(tvbuff_t *tvb, packet_info *pinfo, proto_
     gint64 value;
     protobuf_desc_t pb = { tvb, offset, bytes_left };
     protobuf_tag_t tag = { 0, 0, 0 };
-    wmem_allocator_t *strpool;
-    strpool = wmem_allocator_new(WMEM_ALLOCATOR_SIMPLE);
     guint8* devicename;
     while (protobuf_iter_next(&pb, &tag)) {
         switch(tag.field_number) {
@@ -665,7 +660,7 @@ steamdiscover_dissect_body_authrequest(tvbuff_t *tvb, packet_info *pinfo, proto_
                 value = get_varint64(pb.tvb, pb.offset, pb.bytes_left, &len);
                 proto_tree_add_item(tree, hf_steam_ihs_discovery_body_authrequest_devicename, pb.tvb,
                         pb.offset+len, (gint)value, ENC_UTF_8|ENC_NA);
-                devicename = tvb_get_string_enc(strpool, pb.tvb, pb.offset+len, (gint)value, ENC_UTF_8);
+                devicename = tvb_get_string_enc(wmem_packet_scope(), pb.tvb, pb.offset+len, (gint)value, ENC_UTF_8);
                 if (devicename && strlen(devicename)) {
                     col_append_fstr(pinfo->cinfo, COL_INFO, " from %s", devicename);
                 }
@@ -684,7 +679,6 @@ steamdiscover_dissect_body_authrequest(tvbuff_t *tvb, packet_info *pinfo, proto_
         }
         protobuf_seek_forward(&pb, len);
     }
-    wmem_destroy_allocator(strpool);
 }
 
 /* Dissect a CMsgRemoteDeviceAuthorizationResponse protobuf message body.
-- 
1.7.12.4

