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Return requested size for malloc_usable_size when MALLOC_CHECK_ > 0

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[BZ #1349]

malloc_usable_size returns the usable size in an allocated chunk,
which may be >= the requested size. In the case of MALLOC_CHECK_ being
exported to > 0 however, only the requested size is usable, since a
magic value is written at the end of the request size to trap writes
beyond request bounds. Hence, when MALLOC_CHECK_ is exported to > 0,
malloc_usable_size() should return the request size.
This commit is contained in:
Siddhesh Poyarekar
2012-09-05 21:49:00 +05:30
parent 4d038ae316
commit 6ef9cc37f0
6 changed files with 100 additions and 9 deletions
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5
malloc/malloc.c
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@ -1,5 +1,5 @@
/* Malloc implementation for multiple threads without lock contention.
Copyright (C) 1996-2009, 2010, 2011, 2012 Free Software Foundation, Inc.
Copyright (C) 1996-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Wolfram Gloger <wg@malloc.de>
and Doug Lea <dl@cs.oswego.edu>, 2001.
@ -4563,6 +4563,9 @@ musable(void* mem)
mchunkptr p;
if (mem != 0) {
p = mem2chunk(mem);
if (__builtin_expect(using_malloc_checking == 1, 0))
return malloc_check_get_size(p);
if (chunk_is_mmapped(p))
return chunksize(p) - 2*SIZE_SZ;
else if (inuse(p))