[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH] tools/xenstored: Don't crash xenstored when Live-Update is cancelled

On 17.06.21 19:38, Julien Grall wrote:
From: Julien GralL <jgrall@xxxxxxxxxx>

As Live-Update is asynchronous, it is possible to receive a request to
cancel it (either on the same connection or from a different one).

Currently, this will crash xenstored because do_lu_start() assumes
lu_status will be valid. This is not the case when Live-Update has been
cancelled. This will result to dereference a NULL pointer and
crash Xenstored.

Rework do_lu_start() to check if lu_status is NULL and return an
error in this case.

Fixes: af216a99fb ("tools/xenstore: add the basic framework for doing the live 
Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>


This is currently based on top of:


This can be re-ordered if necessary.
  tools/xenstore/xenstored_control.c | 15 +++++++++++++--
  1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/xenstore/xenstored_control.c 
index a045f102a420..37a3d39f20b5 100644
--- a/tools/xenstore/xenstored_control.c
+++ b/tools/xenstore/xenstored_control.c
@@ -696,7 +696,18 @@ static bool do_lu_start(struct delayed_request *req)
        time_t now = time(NULL);
        const char *ret;
        struct buffered_data *saved_in;
-       struct connection *conn = lu_status->conn;
+       struct connection *conn = req->data;
+       /*
+        * Cancellation may have been requested asynchronously. In this
+        * case, lu_status will be NULL.
+        */
+       if (!lu_status) {
+               ret = "Cancellation was requested";
+               conn = req->data;

This will set conn to the same value it already has.

Other than that:

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature
Description: OpenPGP digital signature



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.