From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Mon, 16 Oct 2017 14:21:59 +0200
Subject: [PATCH] 9pfs: use g_malloc0 to allocate space for xattr

9p back-end first queries the size of an extended attribute,
allocates space for it via g_malloc() and then retrieves its
value into allocated buffer. Race between querying attribute
size and retrieving its could lead to memory bytes disclosure.
Use g_malloc0() to avoid it.

Reported-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
(cherry picked from commit 7bd92756303f2158a68d5166264dc30139b813b6)
---
 hw/9pfs/9p.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 8e9490c5f5..c41c0eb106 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -3236,7 +3236,7 @@ static void coroutine_fn v9fs_xattrwalk(void *opaque)
         xattr_fidp->fid_type = P9_FID_XATTR;
         xattr_fidp->fs.xattr.xattrwalk_fid = true;
         if (size) {
-            xattr_fidp->fs.xattr.value = g_malloc(size);
+            xattr_fidp->fs.xattr.value = g_malloc0(size);
             err = v9fs_co_llistxattr(pdu, &xattr_fidp->path,
                                      xattr_fidp->fs.xattr.value,
                                      xattr_fidp->fs.xattr.len);
@@ -3269,7 +3269,7 @@ static void coroutine_fn v9fs_xattrwalk(void *opaque)
         xattr_fidp->fid_type = P9_FID_XATTR;
         xattr_fidp->fs.xattr.xattrwalk_fid = true;
         if (size) {
-            xattr_fidp->fs.xattr.value = g_malloc(size);
+            xattr_fidp->fs.xattr.value = g_malloc0(size);
             err = v9fs_co_lgetxattr(pdu, &xattr_fidp->path,
                                     &name, xattr_fidp->fs.xattr.value,
                                     xattr_fidp->fs.xattr.len);