linux-kernel - Re: [PATCH] usbnet: Fix a race between usbnet

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]

Message-Id: <20150908.131808.2080207445306948902.davem@davemloft.net>
Date:	Tue, 08 Sep 2015 13:18:08 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eugene.shatokhin@...alab.ru
Cc:	oneukum@...e.de, bjorn@...k.no, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usbnet: Fix a race between usbnet_stop() and the BH

From: Eugene Shatokhin <eugene.shatokhin@...alab.ru>
Date: Tue,  1 Sep 2015 17:05:33 +0300

> The race may happen when a device (e.g. YOTA 4G LTE Modem) is
> unplugged while the system is downloading a large file from the Net.
> 
> Hardware breakpoints and Kprobes with delays were used to confirm that
> the race does actually happen.
> 
> The race is on skb_queue ('next' pointer) between usbnet_stop()
> and rx_complete(), which, in turn, calls usbnet_bh().
> 
> Here is a part of the call stack with the code where the changes to the
> queue happen. The line numbers are for the kernel 4.1.0:
 ...
> As a result, it is possible, for example, that the skb is removed from
> dev->rxq by __skb_unlink() before the check
> "!skb_queue_empty(&dev->rxq)" in usbnet_terminate_urbs() is made. It is
> also possible in this case that the skb is added to dev->done queue
> after "!skb_queue_empty(&dev->done)" is checked. So
> usbnet_terminate_urbs() may stop waiting and return while dev->done
> queue still has an item.
> 
> Locking in defer_bh() and usbnet_terminate_urbs() was revisited to avoid
> this race.
> 
> Signed-off-by: Eugene Shatokhin <eugene.shatokhin@...alab.ru>

Applied, thanks.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/