Expand the over-allocation of image buffers to 32 bytes to attempt to avoid bad reads by swscale.

2 files changed, 12 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index bd7ec7c62..a14a93a0e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2014-06-02  Carl Hetherington  <cth@carlh.net>
+
+	* Empirical hack to prevent over-read of array
+	by libswscale; may fix crashes at the start of
+	DCP encodes.
+
 2014-05-29  Carl Hetherington  <cth@carlh.net>
 
 	* Version 1.69.18 released.
diff --git a/src/lib/image.cc b/src/lib/image.cc
index 1fa55e242..e8622eba4 100644
--- a/src/lib/image.cc
+++ b/src/lib/image.cc
@@ -490,8 +490,13 @@ Image::allocate ()
 		   OS X crashes on this illegal read, though other operating systems don't
 		   seem to mind.  The nasty + 1 in this malloc makes sure there is always a byte
 		   for that instruction to read safely.
+
+		   Further to the above, valgrind is now telling me that ff_rgb24ToY_ssse3
+		   over-reads by more then _avx.  I can't follow the code to work out how much,
+		   so I'll just over-allocate by 32 bytes and have done with it.  Empirical
+		   testing suggests that it works.
 		*/
-		_data[i] = (uint8_t *) wrapped_av_malloc (_stride[i] * lines (i) + 1);
+		_data[i] = (uint8_t *) wrapped_av_malloc (_stride[i] * lines (i) + 32);
 	}
 }