On 10/29/2015 06:44 AM, Markus Armbruster wrote: > 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 <ebl...@redhat.com> > Signed-off-by: Markus Armbruster <arm...@redhat.com> > --- > qobject/json-streamer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Eric Blake <ebl...@redhat.com>
However, a couple comments about the context:
> if (type == JSON_ERROR) {
> goto out_emit_bad;
> } else if (parser->brace_count < 0 ||
> parser->bracket_count < 0 ||
> (parser->brace_count == 0 &&
> parser->bracket_count == 0)) {
> goto out_emit;
Should we go to out_emit_bad for brace_count/bracket_count < 0, and save
out_emit only for the case where brace == bracket == 0? Can we even
trigger negative counts (probably by attempting unpaired "{]]", but will
that trigger earlier errors?)
> } else if (parser->token_size > MAX_TOKEN_SIZE ||
> parser->bracket_count > MAX_NESTING ||
> parser->brace_count > MAX_NESTING) {
> /* Security consideration, we limit total memory allocated per
object
> * and the maximum recursion depth that a message can force.
> */
> goto out_emit;
> }
>
> return;
>
>out_emit_bad:
> /* clear out token list and tell the parser to emit and error
Typo: s/and error/an error/
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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