From 60ad1bad25ea99c538b745ff95e6e0a877d37d1f Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Wed, 27 Jul 2016 07:35:11 +0200 Subject: [PATCH 13/16] qjson: Limit number of tokens in addition to total size RH-Author: Markus Armbruster Message-id: <1469604913-12442-15-git-send-email-armbru@redhat.com> Patchwork-id: 71476 O-Subject: [RHEL-7.3 qemu-kvm PATCH v2 13/15] qjson: Limit number of tokens in addition to total size Bugzilla: 1276036 RH-Acked-by: Miroslav Rezanina RH-Acked-by: John Snow RH-Acked-by: Paolo Bonzini Commit 29c75dd "json-streamer: limit the maximum recursion depth and maximum token count" attempts to guard against excessive heap usage by limiting total token size (it says "token count", but that's a lie). Total token size is a rather imprecise predictor of heap usage: many small tokens use more space than few large tokens with the same input size, because there's a constant per-token overhead: 37 bytes on my system. Tighten this up: limit the token count to 2Mi. Chosen to roughly match the 64MiB total token size limit. Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <1448486613-17634-13-git-send-email-armbru@redhat.com> (cherry picked from commit df649835fe48f635a93316fdefe96ced7189316e) Signed-off-by: Markus Armbruster Signed-off-by: Miroslav Rezanina --- qobject/json-streamer.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c index e87230d..a4db4b8 100644 --- a/qobject/json-streamer.c +++ b/qobject/json-streamer.c @@ -16,6 +16,7 @@ #include "qapi/qmp/json-streamer.h" #define MAX_TOKEN_SIZE (64ULL << 20) +#define MAX_TOKEN_COUNT (2ULL << 20) #define MAX_NESTING (1ULL << 10) static void json_message_free_tokens(JSONMessageParser *parser) @@ -68,6 +69,7 @@ static void json_message_process_token(JSONLexer *lexer, GString *input, parser->bracket_count == 0)) { goto out_emit; } else if (parser->token_size > MAX_TOKEN_SIZE || + g_queue_get_length(parser->tokens) > MAX_TOKEN_COUNT || parser->bracket_count + parser->brace_count > MAX_NESTING) { /* Security consideration, we limit total memory allocated per object * and the maximum recursion depth that a message can force. -- 1.8.3.1