Check bitmap allocation for overflows

This actually fixes #146.

The overflow check itself is obvious. Also, make ass_align() return an
unaligned value if aligning it would overflow. This is probably better,
as it for example makes the overflow check in the caller simpler.

1 files changed, 2 insertions, 0 deletions

diff --git a/libass/ass_utils.h b/libass/ass_utils.h
index 5055e88..1ce451c 100644
--- a/libass/ass_utils.h
+++ b/libass/ass_utils.h
@@ -98,6 +98,8 @@ double ass_strtod(const char *string, char **endPtr);
 
 static inline size_t ass_align(size_t alignment, size_t s)
 {
+    if (s > SIZE_MAX - (alignment - 1))
+        return s;
     return (s + (alignment - 1)) & ~(alignment - 1);
 }