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.
Tighten this up: limit the token count to 128Ki.
If you think 128Ki is too stingy: check-qjson's large_dict test eats a
sweet 500MiB on my machine to parse ~100K tokens. Absurdly wasteful.
Signed-off-by: Markus Armbruster <arm...@redhat.com>
Reviewed-by: Eric Blake <ebl...@redhat.com>
---
qobject/json-streamer.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
index 2bd22a7..8752834 100644
--- a/qobject/json-streamer.c
+++ b/qobject/json-streamer.c
@@ -19,6 +19,7 @@
#include "qapi/qmp/json-streamer.h"
#define MAX_TOKEN_SIZE (64ULL << 20)
+#define MAX_TOKEN_COUNT (128ULL << 10)
#define MAX_NESTING (1ULL << 10)
static void json_message_process_token(JSONLexer *lexer, QString *token,
JSONTokenType type, int x, int y)
@@ -64,6 +65,7 @@ static void json_message_process_token(JSONLexer *lexer,
QString *token, JSONTok
parser->bracket_count == 0)) {
goto out_emit;
} else if (parser->token_size > MAX_TOKEN_SIZE ||
+ qlist_size(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.
--
2.4.3
