linux-kernel - [PATCH 5.11 156/306] kasan: fix memory corruption in kasan_bitops

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Message-Id: <20210315135512.906322942@linuxfoundation.org>
Date:   Mon, 15 Mar 2021 14:53:39 +0100
From:   gregkh@...uxfoundation.org
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrey Konovalov <andreyknvl@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Peter Collingbourne <pcc@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 156/306] kasan: fix memory corruption in kasan_bitops_tags test

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

From: Andrey Konovalov <andreyknvl@...gle.com>

[ Upstream commit e66e1799a76621003e5b04c9c057826a2152e103 ]

Since the hardware tag-based KASAN mode might not have a redzone that
comes after an allocated object (when kasan.mode=prod is enabled), the
kasan_bitops_tags() test ends up corrupting the next object in memory.

Change the test so it always accesses the redzone that lies within the
allocated object's boundaries.

Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a
Link: https://lkml.kernel.org/r/7d452ce4ae35bb1988d2c9244dfea56cf2cc9315.1610733117.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Reviewed-by: Marco Elver <elver@...gle.com>
Reviewed-by: Alexander Potapenko <glider@...gle.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Evgenii Stepanov <eugenis@...gle.com>
Cc: Kevin Brodsky <kevin.brodsky@....com>
Cc: Peter Collingbourne <pcc@...gle.com>
Cc: Vincenzo Frascino <vincenzo.frascino@....com>
Cc: Will Deacon <will.deacon@....com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 lib/test_kasan.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 2947274cc2d3..5a2f104ca13f 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -737,13 +737,13 @@ static void kasan_bitops_tags(struct kunit *test)
 		return;
 	}
 
-	/* Allocation size will be rounded to up granule size, which is 16. */
-	bits = kzalloc(sizeof(*bits), GFP_KERNEL);
+	/* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */
+	bits = kzalloc(48, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits);
 
-	/* Do the accesses past the 16 allocated bytes. */
-	kasan_bitops_modify(test, BITS_PER_LONG, &bits[1]);
-	kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, &bits[1]);
+	/* Do the accesses past the 48 allocated bytes, but within the redone. */
+	kasan_bitops_modify(test, BITS_PER_LONG, (void *)bits + 48);
+	kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, (void *)bits + 48);
 
 	kfree(bits);
 }
-- 
2.30.1