Re: [PATCH] tty: use __GFP_NOWARN for user-controlled kmalloc

[David Rientjes]

On Thu, 4 Feb 2016, Dmitry Vyukov wrote:

> Size of kmalloc() in vc_do_resize() is controlled by user.
> Too large kmalloc() size triggers WARNING message on console.
> 
> Use __GFP_NOWARN for this kmalloc() to not scare admins.
> 

Hmm, this is hitting the WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN)) for 
order >= MAX_ORDER.

vc_do_resize() has

	if (cols > VC_RESIZE_MAXCOL || lines > VC_RESIZE_MAXROW)
		return -EINVAL;

so the appropriate fix would seem to be to reject sizes that would exceed 
the page allocator's ability to return contiguous memory (MAX_ORDER) 
rather than ever trying the allocation in the first place.