linux-kernel - Re: [PATCH net v2] 9p/xen : Fix use after free bug in xen_9pfs_front

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Date:   Mon, 13 Mar 2023 14:30:54 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
Cc:     Zheng Wang <zyytlz.wz@....com>, ericvh@...il.com, lucho@...kov.net,
        asmadeus@...ewreck.org, linux_oss@...debyte.com,
        davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
        v9fs-developer@...ts.sourceforge.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, hackerzheng666@...il.com,
        1395428693sheep@...il.com, alex000young@...il.com
Subject: Re: [PATCH net v2] 9p/xen : Fix use after free bug in
 xen_9pfs_front_remove due  to race condition

On Mon, 13 Mar 2023 14:54:20 +0100 Michal Swiatkowski wrote:
> > @@ -274,12 +274,17 @@ static const struct xenbus_device_id xen_9pfs_front_ids[] = {
> >  static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
> >  {
> >  	int i, j;
> > +	struct xen_9pfs_dataring *ring = NULL;  
> Move it before int i, j to have RCT.
> 
> >  
> >  	write_lock(&xen_9pfs_lock);
> >  	list_del(&priv->list);
> >  	write_unlock(&xen_9pfs_lock);
> >  
> >  	for (i = 0; i < priv->num_rings; i++) {
> > +		/*cancel work*/  
> It isn't needed I think, the function cancel_work_sync() tells everything
> here.

Note that 9p is more storage than networking, so this patch is likely
to go via a different tree than us.