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| author | Markus Armbruster <armbru@redhat.com> | 2015-11-25 22:23:33 +0100 |
|---|---|---|
| committer | Markus Armbruster <armbru@redhat.com> | 2015-11-26 10:07:07 +0100 |
| commit | df649835fe48f635a93316fdefe96ced7189316e (patch) | |
| tree | 5460f95750d89543d73be1b7c125260f1d8e9f47 /qobject/json-streamer.c | |
| parent | 9bada8971173345ceb37ed1a47b00a01a4dd48cf (diff) | |
| download | qemu-df649835fe48f635a93316fdefe96ced7189316e.zip qemu-df649835fe48f635a93316fdefe96ced7189316e.tar.gz qemu-df649835fe48f635a93316fdefe96ced7189316e.tar.bz2 | |
qjson: Limit number of tokens in addition to total size
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 <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1448486613-17634-13-git-send-email-armbru@redhat.com>
Diffstat (limited to 'qobject/json-streamer.c')
| -rw-r--r-- | qobject/json-streamer.c | 2 |
1 files changed, 2 insertions, 0 deletions
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. |