Prevent zero size passed GC_alloc_large if aligned allocation

(fix of commit ba137368d)

* malloc.c (GC_generic_malloc_aligned): If lb is zero then set it to 1
(before rounding it up and converting to granules).
* malloc.c [THREADS] (GC_generic_malloc_aligned): Add assertion to
ensure GRANULES_TO_WORDS(lg)-2 is not negative.

1 files changed, 2 insertions, 0 deletions

diff --git a/malloc.c b/malloc.c
index 8e9b6cce..b1a14778 100644
--- a/malloc.c
+++ b/malloc.c
@@ -229,6 +229,7 @@ GC_INNER void * GC_generic_malloc_aligned(size_t lb, int k, unsigned flags,
         size_t lb_rounded;
         GC_bool init;
 
+        if (EXPECT(0 == lb, FALSE)) lb = 1;
         lg = ALLOC_REQUEST_GRANS(lb);
         lb_rounded = GRANULES_TO_BYTES(lg);
         init = GC_obj_kinds[k].ok_init;
@@ -244,6 +245,7 @@ GC_INNER void * GC_generic_malloc_aligned(size_t lb, int k, unsigned flags,
             BZERO(result, HBLKSIZE * OBJ_SZ_TO_BLOCKS(lb_rounded));
           } else {
 #           ifdef THREADS
+              GC_ASSERT(GRANULES_TO_WORDS(lg) >= 2);
               /* Clear any memory that might be used for GC descriptors */
               /* before we release the lock.                            */
                 ((word *)result)[0] = 0;