Re: [PATCH] prctl: fix PR_SET_MM_AUXV kernel stack leak

Cyrill Gorcunov
2021-03-14T22:19:32Z

On Sun, Mar 14, 2021 at 11:51:14PM +0300, Alexey Dobriyan wrote:
> prctl(PR_SET_MM, PR_SET_MM_AUXV, addr, 1);
>
> will copy 1 byte from userspace to (quite big) on-stack array
> and then stash everything to mm->saved_auxv.
> AT_NULL terminator will be inserted at the very end.
>
> /proc/*/auxv handler will find that AT_NULL terminator
> and copy original stack contents to userspace.
>
> This devious scheme requires CAP_SYS_RESOURCE.
>
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---

Thanks for catching up, Alexey!