Re: [PATCH] platform/chrome: fix double-free in chromeos_laptop_prepare()

[Tzung-Bi Shih]

On Sun, Aug 14, 2022 at 01:08:43AM +0300, Rustam Subkhankulov wrote:
> If chromeos_laptop_prepare_i2c_peripherals() fails after allocating memory
> for 'cros_laptop->i2c_peripherals', this memory is freed at 'err_out' label
> and nonzero value is returned. Then chromeos_laptop_destroy() is called,
> resulting in double-free error.

Alternatively, I would prefer to fix the double-free by setting
`i2c_peripherals` to NULL after [1].

[1]: https://elixir.bootlin.com/linux/v5.19/source/drivers/platform/chrome/chromeos_laptop.c#L787

> Found by Linux Verification Center (linuxtesting.org) with SVACE.

After a quick glance, I found an invalid memory access at [2] if
`i2c_peripherals` is NULL (see [3]).  Do you have a real machine to perform
some module load/unload tests?  Or was the double-free issue discovered by
some static analysis?

[2]: https://elixir.bootlin.com/linux/v5.19/source/drivers/platform/chrome/chromeos_laptop.c#L860
[3]: https://elixir.bootlin.com/linux/v5.19/source/drivers/platform/chrome/chromeos_laptop.c#L756