svn commit: r237017 - stable/9/lib/libc/stdlib

[John Baldwin]

Author: jhb
Date: Wed Jun 13 19:04:39 2012
New Revision: 237017
URL: http://svn.freebsd.org/changeset/base/237017

Log:
  Ensure that the beginning of the DSS is aligned on a chunk boundary.
  If the _end symbol used an address with the low bit set, then the initial
  arena could end up with corrupted rb trees causing a crash during the
  first call to malloc().
  
  This is a direct commit to stable/9 as it does not affect the version
  of malloc in HEAD.
  
  Reviewed by:	jasone
  MFC after:	1 week

Modified:
  stable/9/lib/libc/stdlib/malloc.c

Modified: stable/9/lib/libc/stdlib/malloc.c
==============================================================================
--- stable/9/lib/libc/stdlib/malloc.c	Wed Jun 13 19:00:29 2012	(r237016)
+++ stable/9/lib/libc/stdlib/malloc.c	Wed Jun 13 19:04:39 2012	(r237017)
@@ -5790,6 +5790,9 @@ MALLOC_OUT:
 #ifdef MALLOC_DSS
 	malloc_mutex_init(&dss_mtx);
 	dss_base = sbrk(0);
+	i = (uintptr_t)dss_base & QUANTUM_MASK;
+	if (i != 0)
+		dss_base = sbrk(QUANTUM - i);
 	dss_prev = dss_base;
 	dss_max = dss_base;
 	extent_tree_szad_new(&dss_chunks_szad);