netdev - Re: [PATCH] mISDN: hfcpci: Fix potential deadlock on &hc->lock

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

Date: Wed, 26 Jul 2023 21:46:13 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Chengfeng Ye <dg573847474@...il.com>
Cc: isdn@...ux-pingi.de, alexanderduyck@...com, duoming@....edu.cn,
 yangyingliang@...wei.com, davem@...emloft.net, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mISDN: hfcpci: Fix potential deadlock on &hc->lock

On Tue, 25 Jul 2023 17:37:28 +0000 Chengfeng Ye wrote:
> As &hc->lock is acquired by both timer _hfcpci_softirq() and hardirq
> hfcpci_int(), the timer should disable irq before lock acquisition
> otherwise deadlock could happen if the timmer is preemtped by the hadr irq.
> 
> Possible deadlock scenario:
> hfcpci_softirq() (timer)
>     -> _hfcpci_softirq()
>     -> spin_lock(&hc->lock);  
>         <irq interruption>
>         -> hfcpci_int()
>         -> spin_lock(&hc->lock); (deadlock here)  
> 
> This flaw was found by an experimental static analysis tool I am developing
> for irq-related deadlock.
> 
> The tentative patch fixes the potential deadlock by spin_lock_irq()
> in timer.
> 
> But the patch could be not enough since between the lock critical section
> inside the timer, tx_birq() is called in which a lot of stuff is executed
> such as dev_kfree_skb(). I am not sure what's the best way to solve this
> potential deadlock problem.

Yeah, the dev_kfree_skb() should be dev_kfree_skb_any() or _irq()

> Signed-off-by: Chengfeng Ye <dg573847474@...il.com>

LGTM, but please repost with a Fixes tag added.
-- 
pw-bot: cr