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Remove incorrect alloc_size attribute from pvalloc [BZ #25401]

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pvalloc is guarantueed to round up the allocation size to the page
size, so applications can assume that the memory region is larger
than the passed-in argument.  The alloc_size attribute cannot express
that.

The test case is based on a suggestion from Jakub Jelinek.

This fixes commit 9bf8e29ca1 ("malloc:
make malloc fail with requests larger than PTRDIFF_MAX (BZ#23741)").

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2020-01-17 15:05:34 +01:00
parent 70ba28f7ab
commit 768c83b7f6
3 changed files with 50 additions and 3 deletions
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2
malloc/Makefile
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@ -27,7 +27,7 @@ headers := $(dist-headers) obstack.h mcheck.h
tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
tst-mcheck tst-mallocfork tst-trim1 \
tst-malloc-usable tst-realloc tst-reallocarray tst-posix_memalign \
tst-pvalloc tst-memalign tst-mallopt \
tst-pvalloc tst-pvalloc-fortify tst-memalign tst-mallopt \
tst-malloc-backtrace tst-malloc-thread-exit \
tst-malloc-thread-fail tst-malloc-fork-deadlock \
tst-mallocfork2 \

3
malloc/malloc.h
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@ -71,8 +71,7 @@ extern void *valloc (size_t __size) __THROW __attribute_malloc__
/* Equivalent to valloc(minimum-page-that-holds(n)), that is, round up
__size to nearest pagesize. */
extern void *pvalloc (size_t __size) __THROW __attribute_malloc__
__attribute_alloc_size__ ((1)) __wur;
extern void *pvalloc (size_t __size) __THROW __attribute_malloc__ __wur;
/* Underlying allocation function; successive calls should return
contiguous pieces of memory. */

48
malloc/tst-pvalloc-fortify.c Normal file
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@ -0,0 +1,48 @@
/* Test fortify-source allocation size handling in pvalloc (bug 25401).
Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
#undef _FORTIFY_SOURCE
#define _FORTIFY_SOURCE 2
#include <malloc.h>
#include <string.h>
#include <support/check.h>
#include <support/xunistd.h>
#include <unistd.h>
static int
do_test (void)
{
/* The test below assumes that pvalloc rounds up the allocation size
to at least 8. */
TEST_VERIFY (xsysconf (_SC_PAGESIZE) >= 8);
void *p = pvalloc (5);
TEST_VERIFY_EXIT (p != NULL);
/* This is valid assuming the page size is at least 8 because
pvalloc rounds up the allocation size to a multiple of the page
size. Due to bug 25041, this used to trigger a compiler
warning. */
strcpy (p, "abcdefg");
asm ("" : : "g" (p) : "memory"); /* Optimization barrier. */
TEST_VERIFY (malloc_usable_size (p) >= xsysconf (_SC_PAGESIZE));
return 0;
}
#include <support/test-driver.c>