lkml.org 
[lkml]   [2017]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] mm: Add additional consistency check
    On Fri, 31 Mar 2017 09:40:28 -0700 Kees Cook <keescook@chromium.org> wrote:

    > As found in PaX, this adds a cheap check on heap consistency, just to
    > notice if things have gotten corrupted in the page lookup.

    "As found in PaX" isn't a very illuminating justification for such a
    change. Was there a real kernel bug which this would have exposed, or
    what?

    > --- a/mm/slab.h
    > +++ b/mm/slab.h
    > @@ -384,6 +384,7 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
    > return s;
    >
    > page = virt_to_head_page(x);
    > + BUG_ON(!PageSlab(page));
    > cachep = page->slab_cache;
    > if (slab_equal_or_root(cachep, s))
    > return cachep;

    BUG_ON might be too severe. I expect the kindest VM_WARN_ON_ONCE()
    would suffice here, but without more details it is hard to say.

    \
     
     \ /
      Last update: 2017-03-31 23:34    [W:5.078 / U:0.024 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site