From patchwork Wed May 5 01:40:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12239021 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B5A1C43461 for ; Wed, 5 May 2021 01:40:21 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0E0B661421 for ; Wed, 5 May 2021 01:40:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0E0B661421 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A6B2F6B0105; Tue, 4 May 2021 21:40:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A42366B0107; Tue, 4 May 2021 21:40:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9316C6B0108; Tue, 4 May 2021 21:40:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0116.hostedemail.com [216.40.44.116]) by kanga.kvack.org (Postfix) with ESMTP id 78BDF6B0105 for ; Tue, 4 May 2021 21:40:20 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 39423180AD5C5 for ; Wed, 5 May 2021 01:40:20 +0000 (UTC) X-FDA: 78105472200.27.B5E2837 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf17.hostedemail.com (Postfix) with ESMTP id 6911D40002E1 for ; Wed, 5 May 2021 01:40:15 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 06E7F611AB; Wed, 5 May 2021 01:40:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1620178819; bh=D8bIDYN9Fs8tVciGy1zIl5xoQRfryhpx1Jly6UY+7JQ=; h=Date:From:To:Subject:In-Reply-To:From; b=LFAtMAmThl79kY6Edn5mqulS9N5eLSCygSNLi+6miqBDWEh52fvHZfr3nhgfHSKdx KKrzZcE0DALXUp6vOF2lGcDKXRqP6pKzNRsnGlpQIRyi9kxMtjhcXGgchoo9D/ON4k 0EEmMTEC1TWth2O/tXMhHgmSCrlTE7tp2vGygakg= Date: Tue, 04 May 2021 18:40:18 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, dvyukov@google.com, elver@google.com, glider@google.com, jannh@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 140/143] kfence: zero guard page after out-of-bounds access Message-ID: <20210505014018.iniqSBnhX%akpm@linux-foundation.org> In-Reply-To: <20210504183219.a3cc46aee4013d77402276c5@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LFAtMAmT; spf=pass (imf17.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 6911D40002E1 X-Stat-Signature: yuio1e6y8ohi1tigycc9x7d5bd3dxg7p Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf17; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620178815-998392 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: Marco Elver Subject: kfence: zero guard page after out-of-bounds access After an out-of-bounds accesses, zero the guard page before re-protecting in kfence_guarded_free(). On one hand this helps make the failure mode of subsequent out-of-bounds accesses more deterministic, but could also prevent certain information leaks. Link: https://lkml.kernel.org/r/20210312121653.348518-1-elver@google.com Signed-off-by: Marco Elver Acked-by: Alexander Potapenko Cc: Dmitry Vyukov Cc: Andrey Konovalov Cc: Jann Horn Signed-off-by: Andrew Morton --- mm/kfence/core.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/kfence/core.c~kfence-zero-guard-page-after-out-of-bounds-access +++ a/mm/kfence/core.c @@ -372,6 +372,7 @@ static void kfence_guarded_free(void *ad /* Restore page protection if there was an OOB access. */ if (meta->unprotected_page) { + memzero_explicit((void *)ALIGN_DOWN(meta->unprotected_page, PAGE_SIZE), PAGE_SIZE); kfence_protect(meta->unprotected_page); meta->unprotected_page = 0; }