Messages in this thread | | | Date | Tue, 1 Sep 2015 13:28:20 +0200 | Subject | Re: [PATCH] ps3-vuart: BUG_ON on null drv before dereferencing it on dev_dbg | From | Geert Uytterhoeven <> |
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Hi Colin,
On Tue, Sep 1, 2015 at 12:38 PM, Colin Ian King <colin.king@canonical.com> wrote: > On 01/09/15 11:35, Geert Uytterhoeven wrote: >> 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.
I think this BUG_ON() was purely used during development of the ps3_vuart framework.
Note that the corresponding platform_drv_probe() also just dereferences its driver pointer.
>>> 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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