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From a781053c1b5084ba32b86229b98b9601c990722c Mon Sep 17 00:00:00 2001
From: Markus Armbruster <armbru@redhat.com>
Date: Wed, 27 Jul 2016 07:35:13 +0200
Subject: [PATCH 15/16] json-streamer: fix double-free on exiting during a
 parse

RH-Author: Markus Armbruster <armbru@redhat.com>
Message-id: <1469604913-12442-17-git-send-email-armbru@redhat.com>
Patchwork-id: 71484
O-Subject: [RHEL-7.3 qemu-kvm PATCH v2 15/15] json-streamer: fix double-free on exiting during a parse
Bugzilla: 1276036
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

From: Paolo Bonzini <pbonzini@redhat.com>

Now that json-streamer tries not to leak tokens on incomplete parse,
the tokens can be freed twice if QEMU destroys the json-streamer
object during the parser->emit call.  To fix this, create the new
empty GQueue earlier, so that it is already in place when the old
one is passed to parser->emit.

Reported-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1467636059-12557-1-git-send-email-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit a942d8fa01f65279cdc135f4294db611bbc088ef)
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 qobject/json-streamer.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
index 3c7d6be..7d041e1 100644
--- a/qobject/json-streamer.c
+++ b/qobject/json-streamer.c
@@ -38,6 +38,7 @@ static void json_message_process_token(JSONLexer *lexer, GString *input,
 {
     JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer);
     JSONToken *token;
+    GQueue *tokens;
 
     switch (type) {
     case JSON_LCURLY:
@@ -95,9 +96,12 @@ out_emit:
     /* send current list of tokens to parser and reset tokenizer */
     parser->brace_count = 0;
     parser->bracket_count = 0;
-    /* parser->emit takes ownership of parser->tokens.  */
-    parser->emit(parser, parser->tokens);
+    /* parser->emit takes ownership of parser->tokens.  Remove our own
+     * reference to parser->tokens before handing it out to parser->emit.
+     */
+    tokens = parser->tokens;
     parser->tokens = g_queue_new();
+    parser->emit(parser, tokens);
     parser->token_size = 0;
 }
 
-- 
1.8.3.1