Messages in this thread | | | From | Kees Cook <> | Date | Tue, 29 Nov 2016 11:39:44 -0800 | Subject | Re: [PATCHv4 09/10] mm/usercopy: Switch to using lm_alias |
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On Tue, Nov 29, 2016 at 10:55 AM, Laura Abbott <labbott@redhat.com> wrote: > > The usercopy checking code currently calls __va(__pa(...)) to check for > aliases on symbols. Switch to using lm_alias instead. > > Signed-off-by: Laura Abbott <labbott@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
I should probably add a corresponding alias test to lkdtm...
-Kees
> --- > Found when reviewing the kernel. Tested. > --- > mm/usercopy.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/usercopy.c b/mm/usercopy.c > index 3c8da0a..8345299 100644 > --- a/mm/usercopy.c > +++ b/mm/usercopy.c > @@ -108,13 +108,13 @@ static inline const char *check_kernel_text_object(const void *ptr, > * __pa() is not just the reverse of __va(). This can be detected > * and checked: > */ > - textlow_linear = (unsigned long)__va(__pa(textlow)); > + textlow_linear = (unsigned long)lm_alias(textlow); > /* No different mapping: we're done. */ > if (textlow_linear == textlow) > return NULL; > > /* Check the secondary mapping... */ > - texthigh_linear = (unsigned long)__va(__pa(texthigh)); > + texthigh_linear = (unsigned long)lm_alias(texthigh); > if (overlaps(ptr, n, textlow_linear, texthigh_linear)) > return "<linear kernel text>"; > > -- > 2.7.4 >
-- Kees Cook Nexus Security
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