Fix GC_scratch_last_end_ptr update on GC_scratch_alloc failure

* headers.c (GC_scratch_alloc): Do not update GC_scratch_last_end_ptr
if allocation failed ("result" variable is NULL).

1 files changed, 3 insertions, 1 deletions

diff --git a/headers.c b/headers.c
index 4e2c2d09..87f19782 100644
--- a/headers.c
+++ b/headers.c
@@ -134,7 +134,9 @@ GC_INNER ptr_t GC_scratch_alloc(size_t bytes)
             result = (ptr_t)GET_MEM(bytes_to_get);
             GC_add_to_our_memory(result, bytes_to_get);
             scratch_free_ptr -= bytes;
-            GC_scratch_last_end_ptr = result + bytes;
+            if (result != NULL) {
+                GC_scratch_last_end_ptr = result + bytes;
+            }
             return(result);
         }