Fix linux-user crashes in ioctl(SIOCGIFCONF) when ifc_buf is NULL.
Summary:
This is to fix bug https://bugs.launchpad.net/qemu/+bug/1796754.
It is valid for ifc_buf to be NULL according to
http://man7.org/linux/man-pages/man7/netdevice.7.html.
Signed-off-by: Kan Li <likan_999.student@sina.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20181024201303.114-1-likan_999.student@sina.com>
[lv: fix errors reported by checkpatch.pl]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index bf076cb..08acc4d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4187,28 +4187,33 @@
unlock_user(argptr, arg, 0);
host_ifconf = (struct ifconf *)(unsigned long)buf_temp;
- target_ifc_len = host_ifconf->ifc_len;
target_ifc_buf = (abi_long)(unsigned long)host_ifconf->ifc_buf;
-
target_ifreq_size = thunk_type_size(ifreq_arg_type, 0);
- nb_ifreq = target_ifc_len / target_ifreq_size;
- host_ifc_len = nb_ifreq * sizeof(struct ifreq);
- outbufsz = sizeof(*host_ifconf) + host_ifc_len;
- if (outbufsz > MAX_STRUCT_SIZE) {
- /* We can't fit all the extents into the fixed size buffer.
- * Allocate one that is large enough and use it instead.
- */
- host_ifconf = malloc(outbufsz);
- if (!host_ifconf) {
- return -TARGET_ENOMEM;
+ if (target_ifc_buf != 0) {
+ target_ifc_len = host_ifconf->ifc_len;
+ nb_ifreq = target_ifc_len / target_ifreq_size;
+ host_ifc_len = nb_ifreq * sizeof(struct ifreq);
+
+ outbufsz = sizeof(*host_ifconf) + host_ifc_len;
+ if (outbufsz > MAX_STRUCT_SIZE) {
+ /*
+ * We can't fit all the extents into the fixed size buffer.
+ * Allocate one that is large enough and use it instead.
+ */
+ host_ifconf = malloc(outbufsz);
+ if (!host_ifconf) {
+ return -TARGET_ENOMEM;
+ }
+ memcpy(host_ifconf, buf_temp, sizeof(*host_ifconf));
+ free_buf = 1;
}
- memcpy(host_ifconf, buf_temp, sizeof(*host_ifconf));
- free_buf = 1;
- }
- host_ifc_buf = (char*)host_ifconf + sizeof(*host_ifconf);
+ host_ifc_buf = (char *)host_ifconf + sizeof(*host_ifconf);
- host_ifconf->ifc_len = host_ifc_len;
+ host_ifconf->ifc_len = host_ifc_len;
+ } else {
+ host_ifc_buf = NULL;
+ }
host_ifconf->ifc_buf = host_ifc_buf;
ret = get_errno(safe_ioctl(fd, ie->host_cmd, host_ifconf));
@@ -4231,15 +4236,16 @@
thunk_convert(argptr, host_ifconf, arg_type, THUNK_TARGET);
unlock_user(argptr, arg, target_size);
- /* copy ifreq[] to target user */
-
- argptr = lock_user(VERIFY_WRITE, target_ifc_buf, target_ifc_len, 0);
- for (i = 0; i < nb_ifreq ; i++) {
- thunk_convert(argptr + i * target_ifreq_size,
- host_ifc_buf + i * sizeof(struct ifreq),
- ifreq_arg_type, THUNK_TARGET);
+ if (target_ifc_buf != 0) {
+ /* copy ifreq[] to target user */
+ argptr = lock_user(VERIFY_WRITE, target_ifc_buf, target_ifc_len, 0);
+ for (i = 0; i < nb_ifreq ; i++) {
+ thunk_convert(argptr + i * target_ifreq_size,
+ host_ifc_buf + i * sizeof(struct ifreq),
+ ifreq_arg_type, THUNK_TARGET);
+ }
+ unlock_user(argptr, target_ifc_buf, target_ifc_len);
}
- unlock_user(argptr, target_ifc_buf, target_ifc_len);
}
if (free_buf) {
