qemu_malloc() does not allow size=0 to be passed in and aborts on this behavior.
Unfortunately, there is good reason to believe that within qemu, there are a
number of, so far, undetected places that assume size=0 can be safely passed.
Since we do not want to abort unnecessarily in production builds, return
qemu_malloc(1) whenever the version file indicates that this is a production
build.
Also introduce --enable-zero-malloc/--disable-zero-malloc to make this behavior
overridable.
Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
---
configure | 24 +++++++++++++++++++++++-
qemu-malloc.c | 17 +++++++++++++----
2 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/configure b/configure
index a29839e..ede820e 100755
--- a/configure
+++ b/configure
@@ -256,6 +256,7 @@ blobs="yes"
pkgversion=""
check_utests="no"
user_pie="no"
+zero_malloc=""
# OS specific
if check_define __linux__ ; then
@@ -600,6 +601,10 @@ for opt do
;;
--enable-docs) docs="yes"
;;
+ --enable-zero-malloc) zero_malloc="yes"
+ ;;
+ --disable-zero-malloc) zero_malloc="no"
+ ;;
*) echo "ERROR: unknown option $opt"; show_help="yes"
;;
esac
@@ -752,6 +757,8 @@ echo " --enable-linux-aio enable Linux AIO support"
echo " --enable-io-thread enable IO thread"
echo " --disable-blobs disable installing provided firmware blobs"
echo " --kerneldir=PATH look for kernel includes in PATH"
+echo " --enable-zero-malloc allow allocations of zero size"
+echo " --disable-zero-malloc abort on allocations of zero size"
echo ""
echo "NOTE: The object files are built at the place where configure is
launched"
exit 1
@@ -1792,8 +1799,9 @@ fi
# Consult white-list to determine whether to enable werror
# by default. Only enable by default for git builds
+z_version=`cut -f3 -d. $source_path/VERSION`
+
if test -z "$werror" ; then
- z_version=`cut -f3 -d. $source_path/VERSION`
if test "$z_version" = "50" -a \
"$linux" = "yes" ; then
werror="yes"
@@ -1802,6 +1810,16 @@ if test -z "$werror" ; then
fi
fi
+# Disable zero malloc errors for official releases unless explicitly told to
+# enable/disable
+if test -z "$zero_malloc" ; then
+ if test "$z_version" = "50" ; then
+ zero_malloc="no"
+ else
+ zero_malloc="yes"
+ fi
+fi
+
if test "$werror" = "yes" ; then
QEMU_CFLAGS="-Werror $QEMU_CFLAGS"
fi
@@ -2109,6 +2127,10 @@ fi
echo "CONFIG_UNAME_RELEASE=\"$uname_release\"" >> $config_host_mak
+if test "$zero_malloc" = "yes" ; then
+ echo "CONFIG_ZERO_MALLOC=y" >> $config_host_mak
+fi
+
# USB host support
case "$usb" in
linux)
diff --git a/qemu-malloc.c b/qemu-malloc.c
index 295d185..e82af26 100644
--- a/qemu-malloc.c
+++ b/qemu-malloc.c
@@ -42,21 +42,30 @@ void qemu_free(void *ptr)
free(ptr);
}
+static int allow_zero_malloc(void)
+{
+#if defined(CONFIG_ZERO_MALLOC)
+ return 1;
+#else
+ return 0;
+#endif
+}
+
void *qemu_malloc(size_t size)
{
- if (!size) {
+ if (!size && !allow_zero_malloc()) {
abort();
}
- return oom_check(malloc(size));
+ return oom_check(malloc(size ? size : 1));
}
void *qemu_realloc(void *ptr, size_t size)
{
if (size) {
return oom_check(realloc(ptr, size));
- } else {
+ } else if (allow_zero_malloc()) {
if (ptr) {
- return realloc(ptr, size);
+ return realloc(ptr, size ? size : 1);
}
}
abort();
--
1.6.2.5
