Re: [PATCH] tools/xenstore: fix event sending in introduce_domain()

[Andrew Cooper <amc96@xxxxxxxx>]

On 25/05/2022 11:55, Juergen Gross wrote:
> Commit fc2b57c9af46 ("xenstored: send an evtchn notification on
> introduce_domain") introduced a potential NULL dereference in case of
> Xenstore live update.
>
> Fix that by adding an appropriate check.
>
> Coverity-Id: 1504572
> Fixes: fc2b57c9af46 ("xenstored: send an evtchn notification on 
> introduce_domain")
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> seeing as I've
just looked at the Coverity report too.

CC'ing the others involved in the original patch just so they're aware
it was broken.

~Andrew

> ---
>  tools/xenstore/xenstored_domain.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/tools/xenstore/xenstored_domain.c 
> b/tools/xenstore/xenstored_domain.c
> index de88bf2a68..ead4c237d2 100644
> --- a/tools/xenstore/xenstored_domain.c
> +++ b/tools/xenstore/xenstored_domain.c
> @@ -493,9 +493,11 @@ static struct domain *introduce_domain(const void *ctx,
>               /* Now domain belongs to its connection. */
>               talloc_steal(domain->conn, domain);
>  
> -             /* Notify the domain that xenstore is available */
> -             interface->connection = XENSTORE_CONNECTED;
> -             xenevtchn_notify(xce_handle, domain->port);
> +             if (!restore) {
> +                     /* Notify the domain that xenstore is available */
> +                     interface->connection = XENSTORE_CONNECTED;
> +                     xenevtchn_notify(xce_handle, domain->port);
> +             }
>  
>               if (!is_master_domain && !restore)
>                       fire_watches(NULL, ctx, "@introduceDomain", NULL,