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From: Andrey Konovalov <andreyknvl@google.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
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	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Michal Marek <michal.lkml@markovi.net>,
	"GitAuthor : Andrey Konovalov" <andreyknvl@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Yury Norov <ynorov@caviumnetworks.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Kristina Martsenko <kristina.martsenko@arm.com>,
	Punit Agrawal <punit.agrawal@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Michael Weiser <michael.weiser@gmx.de>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Steve Capper <steve.capper@arm.com>,
	Tyler Baicar <tbaicar@codeaurora.org>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	Paul Lawrence <paullawrence@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Sandipan Das <sandipan@linux.vnet.ibm.com>,
	Kees Cook <keescook@chromium.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	kasan-dev@googlegroups.com, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-sparse@vger.kernel.org,
	linux-mm@kvack.org, linux-kbuild@vger.kernel.org
Cc: Kostya Serebryany <kcc@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Lee Smith <Lee.Smith@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Kees Cook <keescook@google.com>, Jann Horn <jannh@google.com>,
	Mark Brand <markbrand@google.com>
Subject: [RFC PATCH v3 09/15] khwasan, mm: perform untagged pointers comparison in krealloc
Date: Fri, 20 Apr 2018 16:46:47 +0200	[thread overview]
Message-ID: <c39de2d3dac5ff6f2aeb6519c144fb170c673b1a.1524235387.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1524235387.git.andreyknvl@google.com>
In-Reply-To: <cover.1524235387.git.andreyknvl@google.com>

The krealloc function checks where the same buffer was reused or a new one
allocated by comparing kernel pointers. KHWASAN changes memory tag on the
krealloc'ed chunk of memory and therefore also changes the pointer tag of
the returned pointer. Therefore we need to perform comparison on untagged
(with tags reset) pointers to check whether it's the same memory region or
not.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/slab_common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 0582004351c4..451b094b8c5b 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1478,7 +1478,7 @@ void *krealloc(const void *p, size_t new_size, gfp_t flags)
 	}
 
 	ret = __do_krealloc(p, new_size, flags);
-	if (ret && p != ret)
+	if (ret && khwasan_reset_tag(p) != khwasan_reset_tag(ret))
 		kfree(p);
 
 	return ret;
-- 
2.17.0.484.g0c8726318c-goog

  parent reply	other threads:[~2018-04-20 14:46 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20 14:46 [RFC PATCH v3 00/15] khwasan: kernel hardware assisted address sanitizer Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 01/15] khwasan: move common kasan and khwasan code to common.c Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 02/15] khwasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_HW Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 03/15] khwasan, arm64: adjust shadow size for CONFIG_KASAN_HW Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 04/15] khwasan: initialize shadow to 0xff Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 05/15] khwasan, arm64: untag virt address in __kimg_to_phys Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 06/15] khwasan, arm64: fix up fault handling logic Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 07/15] khwasan: add tag related helper functions Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 08/15] khwasan, arm64: enable top byte ignore for the kernel Andrey Konovalov
2018-04-20 14:46 ` Andrey Konovalov [this message]
2018-04-20 14:46 ` [RFC PATCH v3 10/15] khwasan: split out kasan_report.c from report.c Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 11/15] khwasan: add bug reporting routines Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 12/15] khwasan: add hooks implementation Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 13/15] khwasan, arm64: add brk handler for inline instrumentation Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 14/15] khwasan, mm, arm64: tag non slab memory allocated via pagealloc Andrey Konovalov
2018-04-20 14:46 ` [RFC PATCH v3 15/15] khwasan: update kasan documentation Andrey Konovalov

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