This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
[PATCH] Remove incorrect alloc_size attribute from pvalloc [BZ #25401]
- From: Florian Weimer <fweimer at redhat dot com>
- To: libc-alpha at sourceware dot org
- Date: Fri, 17 Jan 2020 11:28:47 +0100
- Subject: [PATCH] Remove incorrect alloc_size attribute from pvalloc [BZ #25401]
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 9bf8e29ca136094f73f69f725f15c51facc97206 ("malloc:
make malloc fail with requests larger than PTRDIFF_MAX (BZ#23741)").
-----
malloc/Makefile | 2 +-
malloc/malloc.h | 3 +--
malloc/tst-pvalloc-fortify.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/malloc/Makefile b/malloc/Makefile
index 734efe368d..984045b5b9 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -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 \
diff --git a/malloc/malloc.h b/malloc/malloc.h
index 0c76264421..a6903fdd54 100644
--- a/malloc/malloc.h
+++ b/malloc/malloc.h
@@ -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. */
diff --git a/malloc/tst-pvalloc-fortify.c b/malloc/tst-pvalloc-fortify.c
new file mode 100644
index 0000000000..391b7fa2f5
--- /dev/null
+++ b/malloc/tst-pvalloc-fortify.c
@@ -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>