linux-kernel - Re: [PATCH v3] watchdog: s3c2410: Fix potential deadlock on &wdt->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]

Message-ID: <f7f1ddb5-a4fd-f79c-f870-8fa7410cd0c7@roeck-us.net>
Date:   Wed, 5 Jul 2023 05:51:41 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Chengfeng Ye <dg573847474@...il.com>,
        krzysztof.kozlowski@...aro.org, alim.akhtar@...sung.com,
        wim@...ux-watchdog.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] watchdog: s3c2410: Fix potential deadlock on
 &wdt->lock

On 7/5/23 02:09, Chengfeng Ye wrote:
> As &wdt->lock is acquired by hard irq s3c2410wdt_irq(),
> other acquisition of the same lock under process context should
> disable irq, otherwise deadlock could happen if the
> irq preempt the execution while the lock is held in process context
> on the same CPU.
> 
> [Deadlock Scenario]
> s3c2410wdt_suspend()
>      -> s3c2410wdt_stop()
>      -> spin_lock(&wdt->lock)
>          <irq iterrupt>
>          -> s3c2410wdt_irq()
>          -> s3c2410wdt_keepalive()
>          -> spin_lock(&wdt->lock) (deadlock here)
> 
> [Deadlock Scenario]
> s3c2410wdt_probe()
>      -> s3c2410wdt_start()
>      -> spin_lock(&wdt->lock)
>          <irq iterrupt>
>          -> s3c2410wdt_irq()
>          -> s3c2410wdt_keepalive()
>          -> spin_lock(&wdt->lock) (deadlock here)
> 
> [Deadlock Scenario]
> s3c2410wdt_keepalive()
>      -> spin_lock(&wdt->lock)
>          <irq iterrupt>
>          -> s3c2410wdt_irq()
>          -> s3c2410wdt_keepalive()
>          -> spin_lock(&wdt->lock) (deadlock here)
> 
> This flaw was found by an experimental static analysis tool I am
> developing for irq-related deadlock, which reported the above
> warning when analyzing the linux kernel 6.4-rc7 release.
> 
> The tentative patch fix the potential deadlock by spin_lock_irqsave()
> under process context.
> 
> Signed-off-by: Chengfeng Ye <dg573847474@...il.com>

I am sure you know what you changed in each version of your patches. I don't.
Please provide change logs when you send new versions of your patches.

Guenter