From: Aaron Barany <aaron.barany@here.com>
Date: Mon, 29 Apr 2019 22:00:30 +0000 (-0700)
Subject: alloc-util: don't use malloc_usable_size() to determine allocated size
X-Git-Tag: v243-rc1~499
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fcc72fd0f103c95810f0335684d0bf6f6ed6481b;p=thirdparty%2Fsystemd.git

alloc-util: don't use malloc_usable_size() to determine allocated size

This reverts commit d4b604baeadbb2498e4f2c3e260260eed210f5d6.

When realloc() is called, the extra memory between the originally
requested size and the end of malloc_usable_size() isn't copied. (at
least with the version of glibc that currently ships on Arch Linux)
As a result, some elements get lost and use uninitialized memory, most
commonly 0, and can lead to crashes.

fixes #12384
---

diff --git a/src/basic/alloc-util.c b/src/basic/alloc-util.c
index 1e4ee722f20..f4bd33f4e01 100644
--- a/src/basic/alloc-util.c
+++ b/src/basic/alloc-util.c
@@ -1,6 +1,5 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
-#include <malloc.h>
 #include <stdint.h>
 #include <string.h>
 
@@ -65,7 +64,7 @@ void* greedy_realloc(void **p, size_t *allocated, size_t need, size_t size) {
                 return NULL;
 
         *p = q;
-        *allocated = _unlikely_(size == 0) ? newalloc : malloc_usable_size(q) / size;
+        *allocated = newalloc;
         return q;
 }