commit ffde3c9f9effcd2b47f5fd76df45551e68c0b1ec
author Philip Withnall <philip@tecnocode.co.uk> Wed Feb 08 21:56:57 2017 +0000
committer Behdad Esfahbod <behdad@behdad.org> Wed Feb 08 13:56:57 2017 -0800
tree 81527e5adc3c2c3ea5e29a2d0a4de77e3e777515
parent 09594df1aecbb7d37093055147c25cc7d7b7fef6

hb-font: Fix a potentially undefined use of memcmp() (#413)

While it’s fine to call memcmp(x, 0, 0) in practice, the C99 standard
explicitly says that this is not allowed: even if the length is zero,
the pointer arguments must be valid.

http://stackoverflow.com/a/16363034

Coverity ID: 141178

Signed-off-by: Philip Withnall <withnall@endlessm.com>

src/hb-font.cc

diff --git a/src/hb-font.cc b/src/hb-font.cc
index a08766f..e900bd3 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -1596,7 +1596,8 @@
 				      unsigned int coords_length)
 {
   if (font->num_coords == coords_length &&
-      0 == memcmp (font->coords, coords, coords_length * sizeof (coords[0])))
+      (coords_length == 0 ||
+       0 == memcmp (font->coords, coords, coords_length * sizeof (coords[0]))))
   {
     free (coords);
     return;