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SubjectRe: [PATCH] ps3-vuart: BUG_ON on null drv before dereferencing it on dev_dbg
On 01/09/15 11:35, Geert Uytterhoeven wrote:
> Hi Colin,
>
> On Tue, Sep 1, 2015 at 12:21 PM, Colin King <colin.king@canonical.com> wrote:
>> On the unlikely event that drv is null, the current code will
>> perform a null pointer dereference with it when printing a dev_dbg
>> message. Instead, the BUG_ON check on drv should be performed
>> before we emit the dev_dbg message.
>
> What about just removing the BUG_ON()?
>
> The system will crash anyway, providing a backtrace.

I personally think a BUG_ON() shows intention to try to catch an
unexpected issue in a standard way as opposed to just removing it and
then hitting an issue with a null ptr deference.

>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>> drivers/ps3/ps3-vuart.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/ps3/ps3-vuart.c b/drivers/ps3/ps3-vuart.c
>> index d6db822..632701a 100644
>> --- a/drivers/ps3/ps3-vuart.c
>> +++ b/drivers/ps3/ps3-vuart.c
>> @@ -1000,12 +1000,11 @@ static int ps3_vuart_probe(struct ps3_system_bus_device *dev)
>> dev_dbg(&dev->core, "%s:%d\n", __func__, __LINE__);
>>
>> drv = ps3_system_bus_dev_to_vuart_drv(dev);
>> + BUG_ON(!drv);
>>
>> dev_dbg(&dev->core, "%s:%d: (%s)\n", __func__, __LINE__,
>> drv->core.core.name);
>>
>> - BUG_ON(!drv);
>> -
>> if (dev->port_number >= PORT_COUNT) {
>> BUG();
>> return -EINVAL;
>
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>



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