From da09cfbf9dcd07c48fe95bdfb2968305de9b9690 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 23 Aug 2018 18:40:15 +0200 Subject: json: Enforce token count and size limits more tightly Token count and size limits exist to guard against excessive heap usage. We check them only after we created the token on the heap. That's assigning a cowboy to the barn to lasso the horse after it has bolted. Close the barn door instead: check before we create the token. Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20180823164025.12553-49-armbru@redhat.com> --- qobject/json-streamer.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) (limited to 'qobject') diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c index 674dfe6e85..810aae521f 100644 --- a/qobject/json-streamer.c +++ b/qobject/json-streamer.c @@ -20,7 +20,7 @@ #define MAX_TOKEN_SIZE (64ULL << 20) #define MAX_TOKEN_COUNT (2ULL << 20) -#define MAX_NESTING (1ULL << 10) +#define MAX_NESTING (1 << 10) static void json_message_free_token(void *token, void *opaque) { @@ -71,6 +71,23 @@ void json_message_process_token(JSONLexer *lexer, GString *input, break; } + /* + * Security consideration, we limit total memory allocated per object + * and the maximum recursion depth that a message can force. + */ + if (parser->token_size + input->len + 1 > MAX_TOKEN_SIZE) { + error_setg(&err, "JSON token size limit exceeded"); + goto out_emit; + } + if (g_queue_get_length(parser->tokens) + 1 > MAX_TOKEN_COUNT) { + error_setg(&err, "JSON token count limit exceeded"); + goto out_emit; + } + if (parser->bracket_count + parser->brace_count > MAX_NESTING) { + error_setg(&err, "JSON nesting depth limit exceeded"); + goto out_emit; + } + token = g_malloc(sizeof(JSONToken) + input->len + 1); token->type = type; memcpy(token->str, input->str, input->len); @@ -91,23 +108,6 @@ void json_message_process_token(JSONLexer *lexer, GString *input, goto out_emit; } - /* - * Security consideration, we limit total memory allocated per object - * and the maximum recursion depth that a message can force. - */ - if (parser->token_size > MAX_TOKEN_SIZE) { - error_setg(&err, "JSON token size limit exceeded"); - goto out_emit; - } - if (g_queue_get_length(parser->tokens) > MAX_TOKEN_COUNT) { - error_setg(&err, "JSON token count limit exceeded"); - goto out_emit; - } - if (parser->bracket_count + parser->brace_count > MAX_NESTING) { - error_setg(&err, "JSON nesting depth limit exceeded"); - goto out_emit; - } - return; out_emit: -- cgit v1.2.3