[Qemu-devel] [PATCH 2/4] json-streamer: Don't crash when input exceeds nesting limit

[Markus Armbruster <armbru@redhat.com>]

We limit nesting depth and input size to defend against input
triggering excessive heap or stack memory use (commit 29c75dd
json-streamer: limit the maximum recursion depth and maximum token
count).  However, when the nesting limit is exceeded,
parser_context_peek_token()'s assertion fails.

Broken in commit 65c0f1e "json-parser: don't replicate tokens at each
level of recursion".

To reproduce stuff 1025 open braces or brackets into QMP.

Fix by taking the error exit instead of the normal one.

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qobject/json-streamer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
index dced2c7..755c74d 100644
--- a/qobject/json-streamer.c
+++ b/qobject/json-streamer.c
@@ -68,7 +68,7 @@ static void json_message_process_token(JSONLexer *lexer, QString *token, JSONTok
         /* Security consideration, we limit total memory allocated per object
          * and the maximum recursion depth that a message can force.
          */
-        goto out_emit;
+        goto out_emit_bad;
     }
 
     return;
-- 
2.4.3