Re: [PATCH RFC 1/6] net: rfkill: gpio: fix gpio name buffer size offby 1
From: Chen-Yu Tsai
Date: Fri Jan 17 2014 - 05:00:01 EST
On Fri, Jan 17, 2014 at 5:46 PM, David Laight <David.Laight@xxxxxxxxxx> wrote:
> From: Chen-Yu Tsai
>> snprintf should be passed the complete size of the buffer, including
>> the space for '\0'. The previous code resulted in the *_reset and
>> *_shutdown strings being truncated.
>> diff --git a/net/rfkill/rfkill-gpio.c b/net/rfkill/rfkill-gpio.c
>> - snprintf(rfkill->reset_name, len + 6 , "%s_reset", rfkill->name);
>> - snprintf(rfkill->shutdown_name, len + 9, "%s_shutdown", rfkill->name);
>> + snprintf(rfkill->reset_name, len + 7 , "%s_reset", rfkill->name);
>> + snprintf(rfkill->shutdown_name, len + 10, "%s_shutdown", rfkill->name);
> I can't find the context for the above, but they look very dubious.
> I'd expect: snprintf(foo, sizeof foo, ...).
> If you are trying to truncate rfkill->name you need to use %.*s.
The driver allocates these buffers on the fly, a few lines above:
len = strlen(rfkill->name);
rfkill->reset_name = devm_kzalloc(&pdev->dev, len + 7, GFP_KERNEL);
rfkill->shutdown_name = devm_kzalloc(&pdev->dev, len + 10, GFP_KERNEL);
I am not trying to truncate rfkill->name. Rather, the buffer length passed
to snprintf was wrong, so the resulting name was truncated by one character.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/