[PATCHv6 10/11] mm/usercopy: Switch to using lm_alias

From: Laura Abbott
Date: Tue Jan 03 2017 - 12:32:43 EST


The usercopy checking code currently calls __va(__pa(...)) to check for
aliases on symbols. Switch to using lm_alias instead.

Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
---
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