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Sun, 1 Dec 2019 01:54:58 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 753B4208C3; Sun, 1 Dec 2019 01:54:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575165297; bh=jgbbAX+heAdcowRF+vVgj0a8bmik7GM/njjLpxxA8wA=; h=Date:From:To:Subject:From; b=Nashcs7FlUqDFKm/dorbC4ZPuhKVK/lOPbQEq3uwmisvHyhMsCyknRBvzCXbcNvFP V4471ZbH7SMHwMmUzGqdS8O2vC7gwrb9iYyLWeDtgRbh68XgNk390nb2yTXN6/8J+x ab0WPfTZ7RdoTZl+VJNIwb0LNGDkRJ3Aov+E14zo= Date: Sat, 30 Nov 2019 17:54:57 -0800 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, aryabinin@virtuozzo.com, christophe.leroy@c-s.fr, dja@axtens.net, dvyukov@google.com, glider@google.com, gor@linux.ibm.com, linux-mm@kvack.org, mark.rutland@arm.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 095/158] fork: support VMAP_STACK with KASAN_VMALLOC Message-ID: <20191201015457.mzKZyzliP%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Daniel Axtens Subject: fork: support VMAP_STACK with KASAN_VMALLOC Supporting VMAP_STACK with KASAN_VMALLOC is straightforward: - clear the shadow region of vmapped stacks when swapping them in - tweak Kconfig to allow VMAP_STACK to be turned on with KASAN Link: http://lkml.kernel.org/r/20191031093909.9228-4-dja@axtens.net Signed-off-by: Daniel Axtens Reviewed-by: Dmitry Vyukov Reviewed-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Christophe Leroy Cc: Mark Rutland Cc: Vasily Gorbik Signed-off-by: Andrew Morton --- arch/Kconfig | 9 +++++---- kernel/fork.c | 4 ++++ 2 files changed, 9 insertions(+), 4 deletions(-) --- a/arch/Kconfig~fork-support-vmap_stack-with-kasan_vmalloc +++ a/arch/Kconfig @@ -843,16 +843,17 @@ config HAVE_ARCH_VMAP_STACK config VMAP_STACK default y bool "Use a virtually-mapped stack" - depends on HAVE_ARCH_VMAP_STACK && !KASAN + depends on HAVE_ARCH_VMAP_STACK + depends on !KASAN || KASAN_VMALLOC ---help--- Enable this if you want the use virtually-mapped kernel stacks with guard pages. This causes kernel stack overflows to be caught immediately rather than causing difficult-to-diagnose corruption. - This is presently incompatible with KASAN because KASAN expects - the stack to map directly to the KASAN shadow map using a formula - that is incorrect if the stack is in vmalloc space. + To use this with KASAN, the architecture must support backing + virtual mappings with real shadow memory, and KASAN_VMALLOC must + be enabled. config ARCH_OPTIONAL_KERNEL_RWX def_bool n --- a/kernel/fork.c~fork-support-vmap_stack-with-kasan_vmalloc +++ a/kernel/fork.c @@ -93,6 +93,7 @@ #include #include #include +#include #include #include @@ -223,6 +224,9 @@ static unsigned long *alloc_thread_stack if (!s) continue; + /* Clear the KASAN shadow of the stack. */ + kasan_unpoison_shadow(s->addr, THREAD_SIZE); + /* Clear stale pointers from reused stack. */ memset(s->addr, 0, THREAD_SIZE);