Re: [patch V2 2/2] x86/ldt: Prevent ldt inheritance on exec

[Thomas Gleixner]

On Fri, 8 Dec 2017, Thomas Gleixner wrote:
> +int ldt_dup_context(struct mm_struct *old_mm, struct mm_struct *mm)
>  {
>       struct ldt_struct *new_ldt;
> -     struct mm_struct *old_mm;
>       int retval = 0;
>  
> -     mutex_init(&mm->context.lock);
> -     old_mm = current->mm;
> -     if (!old_mm) {
> -             mm->context.ldt = NULL;
> +     if (!old_mm)
>               return 0;
> -     }
>  
>       mutex_lock(&old_mm->context.lock);

Bah. That's broken. It now nests into old_mm->mmap_sem which is the reverse
lock order than in ldt_write. Will fix.

Thanks,

        tglx