linux-kernel - Re: [PATCH] speakup: Add spinlock in synth_direct

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Message-ID: <20160905215543.GO4779@var.home>
Date:   Mon, 5 Sep 2016 23:55:43 +0200
From:   Samuel Thibault <samuel.thibault@...-lyon.org>
To:     Pavel Andrianov <andrianov@...ras.ru>
Cc:     William Hubbs <w.d.hubbs@...il.com>,
        Chris Brannon <chris@...-brannons.com>,
        Kirk Reiser <kirk@...sers.ca>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shraddha Barke <shraddha.6596@...il.com>,
        Dilek Uzulmez <dilekuzulmez@...il.com>,
        speakup@...ux-speakup.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, vaishali.thakkar@...cle.com,
        ldv-project@...uxtesting.org
Subject: Re: [PATCH] speakup: Add spinlock in synth_direct_store

Pavel Andrianov, on Mon 05 Sep 2016 16:17:47 +0300, wrote:
> All operations with synth buffer should be protected,
> as there are global pointers, which should be modified atomically.
> 
> Found by Linux Driver Verification project (linuxtesting.org)
> 
> Signed-off-by: Pavel Andrianov <andrianov@...ras.ru>

Reviewed-by: Samuel Thibault <samuel.thibault@...-lyon.org>

> ---
>  drivers/staging/speakup/kobjects.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/staging/speakup/kobjects.c b/drivers/staging/speakup/kobjects.c
> index 528cbdc..7fedee3 100644
> --- a/drivers/staging/speakup/kobjects.c
> +++ b/drivers/staging/speakup/kobjects.c
> @@ -411,11 +411,13 @@ static ssize_t synth_direct_store(struct kobject *kobj,
>  	int len;
>  	int bytes;
>  	const char *ptr = buf;
> +	unsigned long flags;
>  
>  	if (!synth)
>  		return -EPERM;
>  
>  	len = strlen(buf);
> +	spin_lock_irqsave(&speakup_info.spinlock, flags);
>  	while (len > 0) {
>  		bytes = min_t(size_t, len, 250);
>  		strncpy(tmp, ptr, bytes);
> @@ -425,6 +427,7 @@ static ssize_t synth_direct_store(struct kobject *kobj,
>  		ptr += bytes;
>  		len -= bytes;
>  	}
> +	spin_unlock_irqrestore(&speakup_info.spinlock, flags);
>  	return count;
>  }
>  
> -- 
> 2.7.4
> 

-- 
Samuel
Linux, c'est simple : ça s'adresse à une machine qui est parfois un peu
maraboutée mais qui d'habitude n'a pas d'états d'âme. Sur Usenet y'a
plein d'humains et de primates, et ça devient vraiment gore par moment.
-+- TP in : Guide du linuxien pervers - "Le linuxien a-t-il une âme ?" -+-