linux-kernel - [PATCHv6 10/11] mm/usercopy: Switch to using lm

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Date:   Tue,  3 Jan 2017 09:21:52 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Kees Cook <keescook@...omium.org>
Cc:     Laura Abbott <labbott@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCHv6 10/11] mm/usercopy: Switch to using lm_alias

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@....com>
Tested-by: Mark Rutland <mark.rutland@....com>
Acked-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Laura Abbott <labbott@...hat.com>
---
 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