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[66.111.4.26]) by mx.google.com with ESMTPS id u45si5195319qta.73.2019.02.12.23.32.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Feb 2019 23:32:41 -0800 (PST) Received-SPF: neutral (google.com: 66.111.4.26 is neither permitted nor denied by domain of penberg@iki.fi) client-ip=66.111.4.26; Authentication-Results: mx.google.com; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=Yj9LduyX; spf=neutral (google.com: 66.111.4.26 is neither permitted nor denied by domain of penberg@iki.fi) smtp.mailfrom=penberg@iki.fi; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=iki.fi Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id B3AEF21B55; Wed, 13 Feb 2019 02:32:40 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Wed, 13 Feb 2019 02:32:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm2; bh=+/C6EaNfq8gXsgMCYQEEr71KXJaPBdUxGSd0IfnMF lg=; b=Yj9LduyXHslYA/Z15hx4F+BD9rpMYQe0GyOUczRGa0oq4CiMjFVoxHNeR iRBfQ+PkL085aBsS5OQA6H7iWl+Hf3WNeV3HYtIyefbIsrFhF1cjCoNIwLTOOf91 V+N7wTMT2jJpy3vMqYEJM4FOX0t5u2reM4tUSqpizWoTLLLhZxcYIT5gY7ESWnp7 hYgUFaqSzokVqZMHSrD6YfTLukZl53sl5aOwHaXS8qSj2xNKYz2oAq9EFRttLRHO MNpo5drdyFeDvRm64RnR7GxvpmzT1KVtQuwKIDxgq7im7oYvW41uniiH8pdnrSAx aWp65UCyad2yJC9zrLOK5ejloPScg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedtledruddtvddgudduudcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfhuthenuceurghilhhouhhtmecu fedttdenucenucfjughrpefuvfhfhffkffgfgggjtgfgsehtjeertddtfeejnecuhfhroh hmpefrvghkkhgrucfgnhgsvghrghcuoehpvghnsggvrhhgsehikhhirdhfiheqnecukfhp peekledrvdejrdeffedrudejfeenucfrrghrrghmpehmrghilhhfrhhomhepphgvnhgsvg hrghesihhkihdrfhhinecuvehluhhsthgvrhfuihiivgeptd X-ME-Proxy: Received: from Pekka-MacBook.local (89-27-33-173.bb.dnainternet.fi [89.27.33.173]) by mail.messagingengine.com (Postfix) with ESMTPA id 91A47E412E; Wed, 13 Feb 2019 02:32:37 -0500 (EST) Subject: Re: [PATCH] slub: untag object before slab end To: Qian Cai , akpm@linux-foundation.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com Cc: andreyknvl@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20190213020550.82453-1-cai@lca.pw> From: Pekka Enberg Message-ID: Date: Wed, 13 Feb 2019 09:32:32 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190213020550.82453-1-cai@lca.pw> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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: On 13/02/2019 4.05, Qian Cai wrote: > get_freepointer() could return NULL if there is no more free objects in > the slab. However, it could return a tagged pointer (like > 0x2200000000000000) with KASAN_SW_TAGS which would escape the NULL > object checking in check_valid_pointer() and trigger errors below, so > untag the object before checking for a NULL object there. Reviewed-by: Pekka Enberg