Re: [PATCH v3] drivers/iio: Remove all strcpy() uses
From: Andy Shevchenko
Date: Sat Aug 14 2021 - 06:09:47 EST
On Sat, Aug 14, 2021 at 12:06 PM Len Baker <len.baker@xxxxxxx> wrote:
>
> strcpy() performs no bounds checking on the destination buffer. This
> could result in linear overflows beyond the end of the buffer, leading
> to all kinds of misbehaviors. So, remove all the uses and add
> devm_kstrdup() or devm_kasprintf() instead.
>
> This patch is an effort to clean up the proliferation of str*()
> functions in the kernel and a previous step in the path to remove
> the strcpy function from the kernel entirely [1].
>
> [1] https://github.com/KSPP/linux/issues/88
Thanks for an update, my comments below.
...
> This patch doesn't change the logic. I think it is better to use the
> current logic and not use always the plus and minus signs as suggested
> in the previous version. I don't like the idea that 0 has sign.
Agree on that, the safest way to go with.
...
> const char *orient;
> char *str;
> int i;
> + struct device *dev;
Please, keep this in reversed xmas tree order (longer lines first).
...
> + dev = regmap_get_device(st->map);
I haven't checked the code in between, but maybe it's possible to move
an assignment directly to the definition block above.
...
> + /*
> + * The value is inverted according to the following
"to one of the"
And technically speaking "inversion" is not the same as negation
(which is "sign inversion").
> + * rules:
> + *
> + * 1) Drop leading minus.
> + * 2) Add leading minus.
> + * 3) Leave 0 as is.
> + */
> + if (orient[0] == '-')
> + str = devm_kstrdup(dev, orient + 1, GFP_KERNEL);
> + else if (orient[0] != '0' || orient[1] != '\0')
> + str = devm_kasprintf(dev, GFP_KERNEL, "-%s", orient);
I would go with the logic I suggested later on, i.e.
else if (orient[0] == '0' && orient[1] == '\0')
str = devm_kstrdup(dev, orient, GFP_KERNEL);
and below changed accordingly. It will clarify the "0" check.
> + else
> + str = devm_kstrdup(dev, orient, GFP_KERNEL);
> +
Redundant blank line.
> + if (!str)
> return -ENOMEM;
--
With Best Regards,
Andy Shevchenko