From 467e7822a975fa3ed740144cd849ab596ab30118 Mon Sep 17 00:00:00 2001 From: Uli Schlachter Date: Fri, 25 Dec 2020 16:09:19 +0100 Subject: [PATCH] Add a bounds check to cairo_cff_parse_charstring() The code in cairo-cff-subset.c parses a binary font format without seeming to bother much verifying the data. The result is that poppler can be used to cause an out-of-bounds access in cairo_cff_parse_charstring() via a crafted font file. Fix this by adding the needed length check. The other code in the file also contains lots of similar things. Since I cannot really fix everything properly, I'll just fix the one instance that was found by a fuzzer. No testcase is added, because this depends on a broken font that is quite large. Adding something this big to the test suite does not seem sensible. Fixes: https://gitlab.freedesktop.org/cairo/cairo/-/issues/444 Signed-off-by: Uli Schlachter --- src/cairo-cff-subset.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/cairo-cff-subset.c b/src/cairo-cff-subset.c index fce4195e9..f85190f77 100644 --- a/src/cairo-cff-subset.c +++ b/src/cairo-cff-subset.c @@ -1604,6 +1604,8 @@ cairo_cff_parse_charstring (cairo_cff_font_t *font, } } else { sub_num = font->type2_stack_top_value + font->local_sub_bias; + if (sub_num >= _cairo_array_num_elements(&font->local_sub_index)) + return CAIRO_INT_STATUS_UNSUPPORTED; element = _cairo_array_index (&font->local_sub_index, sub_num); if (! font->local_subs_used[sub_num] || (need_width && !font->type2_found_width))