| Message ID | 1480445729-27130-10-git-send-email-labbott@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 >
On Tue, Nov 29, 2016 at 10:55:28AM -0800, Laura Abbott 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> I've given this a go on Juno, which boots happily. LKDTM triggers as expected when copying from the kernel text and its alias. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Thanks, Mark. > --- > 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 >
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>";
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> --- Found when reviewing the kernel. Tested. --- mm/usercopy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)