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

[Cyrill Gorcunov]

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@xxxxxxxxx>
> ---

Thanks for catching up, Alexey!