[Xen-devel] [PATCHv1] xenbus: Add proper handling of XS_ERROR from Xenbus for transactions.

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: Jennifer Herbert <Jennifer.Herbert@xxxxxxxxxx>

If Xenstore sends back a XS_ERROR for TRANSACTION_END, the driver BUGs
because it cannot find the matching transaction in the list.  For
TRANSACTION_START, it leaks memory.

Check the message as returned from xenbus_dev_request_and_reply(), and
clean up for TRANSACTION_START or discard the error for
TRANSACTION_END.

Signed-off-by: Jennifer Herbert <Jennifer.Herbert@xxxxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 drivers/xen/xenbus/xenbus_dev_frontend.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c 
b/drivers/xen/xenbus/xenbus_dev_frontend.c
index 85534ea..9433e46 100644
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -326,10 +326,13 @@ static int xenbus_write_transaction(unsigned msg_type,
        }
 
        if (msg_type == XS_TRANSACTION_START) {
-               trans->handle.id = simple_strtoul(reply, NULL, 0);
-
-               list_add(&trans->list, &u->transactions);
-       } else if (msg_type == XS_TRANSACTION_END) {
+               if (u->u.msg.type == XS_ERROR)
+                       kfree(trans);
+               else {
+                       trans->handle.id = simple_strtoul(reply, NULL, 0);
+                       list_add(&trans->list, &u->transactions);
+               }
+       } else if (u->u.msg.type == XS_TRANSACTION_END) {
                list_for_each_entry(trans, &u->transactions, list)
                        if (trans->handle.id == u->u.msg.tx_id)
                                break;
-- 
1.7.10.4


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