Re: [PATCH v2 4/4] gpio: pca953x: fix an incorrect lockdep warning

[Geert Uytterhoeven]

On Sat, Sep 24, 2016 at 11:15 AM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote:
>>  drivers/gpio/gpio-pca953x.c | 2 ++
>>  1 file changed, 2 insertions(+)
>
> FYI, my code checkers found this in this driver:
>
>     SMATCH
> drivers/gpio/gpio-pca953x.c:562 pca953x_irq_pending() error: buffer overflow 'cur_stat' 5 <= 8191
> drivers/gpio/gpio-pca953x.c:573 pca953x_irq_pending() warn: buffer overflow 'old_stat' 5 <= 8191
>
> Didn't check further. I fixed a sparse warning, though.

I guess those lines are

        memcpy(old_stat, chip->irq_stat, NBANK(chip));

and

        memcpy(chip->irq_stat, cur_stat, NBANK(chip));

?

#define NBANK(chip) DIV_ROUND_UP(chip->gpio_chip.ngpio, BANK_SZ)

ngpio is u16, BANK_SZ is 8, so smatch assumes someone may set
ngpio to 65535. Which someone could do through driver_data.
But none of the predefined entries in pca953x_dt_ids[] does.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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