linux-kernel - Re: [RESEND][PATCH] scsi: esas2r: fix potential format string flaw

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Date:	Wed, 18 Dec 2013 10:01:00 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Bradley Grove <linuxdrivers@...otech.com>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	linux-scsi@...r.kernel.org
Subject: Re: [RESEND][PATCH] scsi: esas2r: fix potential format string flaw

On Tue, Dec 17, 2013 at 9:42 PM, Joe Perches <joe@...ches.com> wrote:
> On Tue, 2013-12-17 at 10:27 -0800, Kees Cook wrote:
>> This makes sure format strings cannot leak into the printk call via the
>> constructed buffer.
> []
>> diff --git a/drivers/scsi/esas2r/esas2r_log.c b/drivers/scsi/esas2r/esas2r_log.c
> []
>> @@ -171,7 +171,7 @@ static int esas2r_log_master(const long level,
>>               if (strlen(event_buffer) < buflen)
>>                       strcat(buffer, "\n");
>>
>> -             printk(event_buffer);
>> +             printk("%s", event_buffer);
>
> It's probably better to remove the
>
>                 if (strlen(event_buffer) < buflen)
>                         strcat(buffer, "\n");
>
> and use
>
>         printk("%s\n", event_buffer);
>
> so that the output is always newline terminated.

Ah! Yes, good call.

-Kees

-- 
Kees Cook
Chrome OS Security
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