[babl] babl: slightly pad source buffers for creating conversions

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 411dae60ae1c564090fa7c6a3943550ec1f1d1be
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu May 14 17:53:50 2020 +0200

    babl: slightly pad source buffers for creating conversions
    
    This is done because many babls conversions get optimized by C compilers
    to read 16bytes of data at a time. Causing valgrind to report
    "Invalid read of size 16" as a false positive. By padding the data at
    least when creating conversions we mask the false positives.

 babl/babl-conversion.c     | 4 +++-
 babl/babl-fish-reference.c | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/babl/babl-conversion.c b/babl/babl-conversion.c
index 7cca1f248..6c5d4f16b 100644
--- a/babl/babl-conversion.c
+++ b/babl/babl-conversion.c
@@ -487,7 +487,9 @@ babl_conversion_error (BablConversion *conversion)
       conversion->error = 0.0000042;
     }
 
-  source                      = babl_calloc (test_pixels, fmt_source->format.bytes_per_pixel);
+  source                      = babl_calloc (test_pixels+1, fmt_source->format.bytes_per_pixel);
+                                                 /* +1 is masking valgrind Invalid read of 16
+                                                  *    false positives */
   destination                 = babl_calloc (test_pixels, fmt_destination->format.bytes_per_pixel);
   ref_destination             = babl_calloc (test_pixels, fmt_destination->format.bytes_per_pixel);
   destination_rgba_double     = babl_calloc (test_pixels, fmt_rgba_double->format.bytes_per_pixel);
diff --git a/babl/babl-fish-reference.c b/babl/babl-fish-reference.c
index f641a2150..a62f32ae1 100644
--- a/babl/babl-fish-reference.c
+++ b/babl/babl-fish-reference.c
@@ -1259,7 +1259,8 @@ babl_fish_reference_process_float (const Babl *babl,
     }
     else
     {
-      source_float_buf_alloc = babl_malloc (sizeof (float) * n *
+      /* the +1 is to mask a valgrind 'invalid read of size 16' false positive  */
+      source_float_buf_alloc = babl_malloc (sizeof (float) * (n+1) *
                                   (BABL (babl->fish.source)->format.model->components));
 
       source_float_buf = source_float_buf_alloc;