File 0172-9pfs-local-statfs-don-t-follow-syml.patch of Package qemu.5923

From 970e579d3bf0ab7d4b99309b9447e0487b6f4035 Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Sun, 26 Feb 2017 23:43:25 +0100
Subject: [PATCH] 9pfs: local: statfs: don't follow symlinks

The local_statfs() callback is vulnerable to symlink attacks because it
calls statfs() which follows symbolic links in all path elements.

This patch converts local_statfs() to rely on open_nofollow() and fstatfs()
instead.

This partly fixes CVE-2016-9602.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 31e51d1c15b35dc98b88a301812914b70a2b55dc)
[BR: Fix and/or infrastructure for BSC#1020427 CVE-2016-9602]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/9pfs/9p-local.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 4b2720557a..b7a9007818 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -1076,13 +1076,11 @@ static int local_fsync(FsContext *ctx, int fid_type,
 
 static int local_statfs(FsContext *s, V9fsPath *fs_path, struct statfs *stbuf)
 {
-    char *buffer;
-    int ret;
-    char *path = fs_path->data;
+    int fd, ret;
 
-    buffer = rpath(s, path);
-    ret = statfs(buffer, stbuf);
-    g_free(buffer);
+    fd = local_open_nofollow(s, fs_path->data, O_RDONLY, 0);
+    ret = fstatfs(fd, stbuf);
+    close_preserve_errno(fd);
     return ret;
 }