Properly handle fencepost with MALLOC_ALIGN_MASK

diff --git a/ChangeLog b/ChangeLog
index b8c492e..e3329b4 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-09-24  H.J. Lu  <hongjiu.lu@intel.com>
+
+       [BZ #14562]
+       * malloc/arena.c (heap_trim): Properly get fencepost and adjust
+       new chunk size with MALLOC_ALIGN_MASK.
+
 2012-09-24  Joseph Myers  <joseph@codesourcery.com>
 
        [BZ #5044]

diff --git a/NEWS b/NEWS
index 84c05d5..33f86a1 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -14,7 +14,7 @@ Version 2.17
   14151, 14154, 14157, 14166, 14173, 14195, 14237, 14252, 14283, 14298,
   14303, 14307, 14328, 14331, 14336, 14337, 14347, 14349, 14459, 14476,
   14505, 14510, 14516, 14518, 14519, 14532, 14538, 14544, 14545, 14576,
-  14579, 14583, 14587.
+  14579, 14583, 14587, 14562.
 
 * Support for STT_GNU_IFUNC symbols added for s390 and s390x.
   Optimized versions of memcpy, memset, and memcmp added for System z10 and

diff --git a/malloc/arena.c b/malloc/arena.c
index 97c0b90..f24e76c 100644 (file)
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -655,15 +655,19 @@ heap_trim(heap_info *heap, size_t pad)
   unsigned long pagesz = GLRO(dl_pagesize);
   mchunkptr top_chunk = top(ar_ptr), p, bck, fwd;
   heap_info *prev_heap;
-  long new_size, top_size, extra;
+  long new_size, top_size, extra, prev_size, misalign;
 
   /* Can this heap go away completely? */
   while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) {
     prev_heap = heap->prev;
-    p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ));
+    prev_size = prev_heap->size - (MINSIZE-2*SIZE_SZ);
+    p = chunk_at_offset(prev_heap, prev_size);
+    /* fencepost must be properly aligned.  */
+    misalign = ((long) p) & MALLOC_ALIGN_MASK;
+    p = chunk_at_offset(prev_heap, prev_size - misalign);
     assert(p->size == (0|PREV_INUSE)); /* must be fencepost */
     p = prev_chunk(p);
-    new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ);
+    new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ) + misalign;
     assert(new_size>0 && new_size<(long)(2*MINSIZE));
     if(!prev_inuse(p))
       new_size += p->prev_size;