Re: [PATCH] mm: larger stack guard gap, between vmas

[Willy Tarreau]

On Tue, Jul 04, 2017 at 12:36:11PM +0100, Ben Hutchings wrote:
> > If anywhing this would require to have a loop over all PROT_NONE
> > mappings to not hit into other weird usecases.
> 
> That's what I was thinking of.  Tried the following patch:
(...)
> -	next = vma->vm_next;
> +	/*
> +	 * Allow VM_NONE mappings in the gap as some applications try
> +	 * to make their own stack guards
> +	 */
> +	for (next = vma->vm_next;
> +	     next && !(next->vm_flags & (VM_READ | VM_WRITE | VM_EXEC));
> +	     next = next->vm_next)
> +		;

That's what I wanted to propose but I feared someone would scream at me
for this loop :-)

+1 for me!

Willy