Re: [PATCH (resend)] Input: MT - limit max slots

Tetsuo Handa
2024-07-30T05:38:36Z

On 2024/07/30 2:59, Dmitry Torokhov wrote:
> Please do not. Or you will have to patch it again when we will still see
> the same allocation failures because someone requested an input device
> with "too many" slots (1024 results in 4Mb mt->red table for example).
>
> Just fix malloc/syzkaller not to trigger on benign memory allocation
> hickups. They are normal.

I chose 1024 because as far as I know 4MB is max acceptable size for
all environments without triggering too large allocation warning.

You worry about mt->red, but did you notice that syzbot was reporting that
memory allocation for mt->red has an integer overflow bug, which can cause
out of bounds write or ZERO_SIZE_PTR pointer dereference bug at input_mt_set_matrix() ?

https://lkml.kernel.org/r/6d878e01-6c2f-8766-2578-c95030442369@I-love.SAKURA.ne.jp

Lucky thing is that the uinput interface is for only the "root" user...