| Message ID | 1441102876-26978-1-git-send-email-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
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. > 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
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 >
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
On Tue, 2015-09-01 at 11:21 +0100, Colin King 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. > > Signed-off-by: Colin Ian King <colin.king@canonical.com> I applied this to my ps3-linux repo. I can update it if you decide to do the other fixes Geert mentioned. -Geoff
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;