Validate cache more carefully
Reject caches when FcPattern isn't a constant.
This is usually unlikely to happen but reported.
I've decided to add more validation since this isn't reproducible
and easy to have a workaround rather than investigating 'why'.
https://bugs.freedesktop.org/show_bug.cgi?id=103237
diff --git a/src/fccache.c b/src/fccache.c
index 6f3c68a..c59ea19 100644
--- a/src/fccache.c
+++ b/src/fccache.c
@@ -646,7 +646,8 @@
(char *) font > end - sizeof (FcFontSet) ||
font->elts_offset < 0 ||
font->elts_offset > end - (char *) font ||
- font->num > (end - (char *) font - font->elts_offset) / sizeof (FcPatternElt))
+ font->num > (end - (char *) font - font->elts_offset) / sizeof (FcPatternElt) ||
+ !FcRefIsConst (&font->ref))
return FcFalse;