[PATCH] xen: xenbus_dev_frontend: Really return response string

[Simon Gaiser]

xenbus_command_reply() did not actually copy the response string and
leaked stack content instead.

Fixes: 9a6161fe73bd ("xen: return xenstore command failures via response 
instead of rc")
Signed-off-by: Simon Gaiser <si...@invisiblethingslab.com>
---

PS: AFAICS this is not a security issue since /dev/xen/xenbus is
normally only accessible by root and giving xenstore access to a less
trusted entity probably has a bunch of other unintended consequences.

 drivers/xen/xenbus/xenbus_dev_frontend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c 
b/drivers/xen/xenbus/xenbus_dev_frontend.c
index a493e99bed21..845a70fa7f79 100644
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -403,7 +403,7 @@ static int xenbus_command_reply(struct xenbus_file_priv *u,
 {
        struct {
                struct xsd_sockmsg hdr;
-               const char body[16];
+               char body[16];
        } msg;
        int rc;
 
@@ -412,6 +412,7 @@ static int xenbus_command_reply(struct xenbus_file_priv *u,
        msg.hdr.len = strlen(reply) + 1;
        if (msg.hdr.len > sizeof(msg.body))
                return -E2BIG;
+       memcpy(&msg.body, reply, msg.hdr.len);
 
        mutex_lock(&u->reply_mutex);
        rc = queue_reply(&u->read_buffers, &msg, sizeof(msg.hdr) + msg.hdr.len);
-- 
2.16.2