[PATCH] tools/xenstored: Correctly read the requests header from the stream

[Julien Grall <julien@xxxxxxx>]

From: Julien Grall <jgrall@xxxxxxxxxx>

Commit c0fe360f42 ("tools/xenstored: Extend restore code to handle
multiple input buffer") extend the read_buffered_state() to support
multiple input buffers. Unfortunately, the commit didn't go far
enough and still used sc->data (start of the buffers) for retrieving
the header. This would lead to read the wrong headers for second and
follow-up commands.

Use data in place for sc->data for the source of the memcpy()s.

Fixes: c0fe360f42 ("tools/xenstored: Extend restore code to handle multiple 
input buffer")
Reported-by: Raphael Ning <raphning@xxxxxxxxxx>
Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

----

I unfortunately didn't spot the issue because I forgot to check whether
the REQ ID of the responses were unique.
---
 tools/xenstore/xenstored_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index cf7297a96cb1..16c856730c55 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -2717,11 +2717,11 @@ void read_state_buffered_data(const void *ctx, struct 
connection *conn,
                len = sc->data_in_len - (data - sc->data);
                if (len < sizeof(bdata->hdr)) {
                        bdata->inhdr = true;
-                       memcpy(&bdata->hdr, sc->data, len);
+                       memcpy(&bdata->hdr, data, len);
                        bdata->used = len;
                } else {
                        bdata->inhdr = false;
-                       memcpy(&bdata->hdr, sc->data, sizeof(bdata->hdr));
+                       memcpy(&bdata->hdr, data, sizeof(bdata->hdr));
                        if (bdata->hdr.msg.len <= DEFAULT_BUFFER_SIZE)
                                bdata->buffer = bdata->default_buffer;
                        else
-- 
2.17.1