Re: [PATCH] input: cyapa_gen6: fix out-of-bounds stack access

[Dmitry Torokhov]

On Mon, Oct 26, 2020 at 05:13:29PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> gcc -Warray-bounds warns about a serious bug in
> cyapa_pip_retrieve_data_structure:
> 
> drivers/input/mouse/cyapa_gen6.c: In function 'cyapa_pip_retrieve_data_structure.constprop':
> include/linux/unaligned/access_ok.h:40:17: warning: array subscript -1 is outside array bounds of 'struct retrieve_data_struct_cmd[1]' [-Warray-bounds]
>    40 |  *((__le16 *)p) = cpu_to_le16(val);
> drivers/input/mouse/cyapa_gen6.c:569:13: note: while referencing 'cmd'
>   569 |  } __packed cmd;
>       |             ^~~
> 
> Apparently the '-2' was added to the pointer instead of the value,
> writing garbage into the stack next to this variable.
> 
> Fixes: c2c06c41f700 ("Input: cyapa - add gen6 device module support")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Applied, thank you.

-- 
Dmitry