Re: [PATCHv4 09/10] mm/usercopy: Switch to using lm_alias
From: Mark Rutland <mark.rutland@arm.com>
Date: 2016-12-06 18:21:19
Also in:
linux-arm-kernel, lkml
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 <redacted>
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.
quoted hunk ↗ jump to hunk
--- 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
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