[PATCHv4 09/10] mm/usercopy: Switch to using lm_alias
From: Laura Abbott <hidden>
Date: 2016-11-29 18:57:11
Also in:
linux-mm, lkml
Subsystem:
kernel hardening (not covered by other areas), memory management, the rest · Maintainers:
Kees Cook, Andrew Morton, Linus Torvalds
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 <redacted> --- 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