svn commit: r262545 - stable/9/libexec/rtld-elf

[David Xu]

Author: davidxu
Date: Thu Feb 27 02:41:41 2014
New Revision: 262545
URL: http://svnweb.freebsd.org/changeset/base/262545

Log:
  MFC r262277:
  
  malloc_aligned() may not leave enough space for pointer to allocated memory,
  saving the pointer will overwrite bytes belongs to another memory block
  unexpectly, to fix the problem, use (allocated address + sizeof(void *)) as
  initial value, and slip to next aligned address, so maximum extra bytes is
  sizeof(void *) + align - 1.
  
  Tested by: Andre Albsmeier < mail at ma17 dot ata dot myota dot orgndre >
  
  MFC r262334:
  
  Increase alignment to size of pointer if the alignment is too small.
  Some modules do not align data at least to size of pointer, they uses a
  smaller alignment, but our pointer should be aligned to its native
  boundary, otherwise on some platforms, hardware alignment checking
  will cause bus error.

Modified:
  stable/9/libexec/rtld-elf/xmalloc.c
Directory Properties:
  stable/9/   (props changed)
  stable/9/libexec/rtld-elf/   (props changed)

Modified: stable/9/libexec/rtld-elf/xmalloc.c
==============================================================================
--- stable/9/libexec/rtld-elf/xmalloc.c	Thu Feb 27 02:36:09 2014	(r262544)
+++ stable/9/libexec/rtld-elf/xmalloc.c	Thu Feb 27 02:41:41 2014	(r262545)
@@ -72,14 +72,12 @@ void *
 malloc_aligned(size_t size, size_t align)
 {
 	void *mem, *res;
-	uintptr_t x;
-	size_t asize, r;
 
-	r = round(sizeof(void *), align);
-	asize = round(size, align) + r;
-	mem = xmalloc(asize);
-	x = (uintptr_t)mem;
-	res = (void *)round(x, align);
+	if (align < sizeof(void *))
+		align = sizeof(void *);
+
+	mem = xmalloc(size + sizeof(void *) + align - 1);
+	res = (void *)round((uintptr_t)mem + sizeof(void *), align);
 	*(void **)((uintptr_t)res - sizeof(void *)) = mem;
 	return (res);
 }