netdev - Re: [PATCH net] xen-netback: avoid race that can lead to NULL pointer dereference

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Thu, 12 Dec 2019 11:00:19 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     pdurrant@...zon.com
Cc:     netdev@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, jgross@...e.com,
        jakub.kicinski@...ronome.com, wei.liu@...nel.org
Subject: Re: [PATCH net] xen-netback: avoid race that can lead to NULL
 pointer dereference

From: Paul Durrant <pdurrant@...zon.com>
Date: Thu, 12 Dec 2019 12:37:23 +0000

> Commit 2ac061ce97f4 ("xen/netback: cleanup init and deinit code")
> introduced a problem. In function xenvif_disconnect_queue(), the value of
> queue->rx_irq is zeroed *before* queue->task is stopped. Unfortunately that
> task may call notify_remote_via_irq(queue->rx_irq) and calling that
> function with a zero value results in a NULL pointer dereference in
> evtchn_from_irq().
> 
> This patch simply re-orders things, stopping all tasks before zero-ing the
> irq values, thereby avoiding the possibility of the race.
> 
> Signed-off-by: Paul Durrant <pdurrant@...zon.com>

Please repost this with an appropriate Fixes: tag.

And then you can removed the explicit commit reference from the log message
and simply say "The commit mentioned in the Fixes tag introduced a problen ..."