From mboxrd@z Thu Jan 1 00:00:00 1970 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 A99F2C11F65 for ; Wed, 30 Jun 2021 13:53:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E8AA61374 for ; Wed, 30 Jun 2021 13:53:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235765AbhF3N4Q (ORCPT ); Wed, 30 Jun 2021 09:56:16 -0400 Received: from mailgw02.mediatek.com ([210.61.82.184]:36743 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S235497AbhF3NwT (ORCPT ); Wed, 30 Jun 2021 09:52:19 -0400 X-UUID: e7d4bf8d56984e219f26e258a12eef49-20210630 X-UUID: e7d4bf8d56984e219f26e258a12eef49-20210630 Received: from mtkcas06.mediatek.inc [(172.21.101.30)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1842347633; Wed, 30 Jun 2021 21:49:47 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs02n2.mediatek.inc (172.21.101.101) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 30 Jun 2021 21:49:45 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 30 Jun 2021 21:49:45 +0800 From: To: CC: , Yee Lee , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Matthias Brugger , "open list:KASAN" , "open list:MEMORY MANAGEMENT" , open list , "moderated list:ARM/Mediatek SoC support" , "moderated list:ARM/Mediatek SoC support" Subject: [PATCH v3 1/1] kasan: Add memzero init for unaligned size under SLUB debug Date: Wed, 30 Jun 2021 21:49:40 +0800 Message-ID: <20210630134943.20781-2-yee.lee@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20210630134943.20781-1-yee.lee@mediatek.com> References: <20210630134943.20781-1-yee.lee@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yee Lee Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite the redzone of object with unaligned size. An additional memzero_explicit() path is added to replacing init by hwtag instruction for those unaligned size at SLUB debug mode. The penalty is acceptable since they are only enabled in debug mode, not production builds. A block of comment is added for explanation. Signed-off-by: Yee Lee Suggested-by: Marco Elver Suggested-by: Andrey Konovalov Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Andrew Morton --- mm/kasan/kasan.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 8f450bc28045..6f698f13dbe6 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -387,6 +387,16 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init) if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK)) return; + /* + * Explicitly initialize the memory with the precise object size + * to avoid overwriting the SLAB redzone. This disables initialization + * in the arch code and may thus lead to performance penalty. + * The penalty is accepted since SLAB redzones aren't enabled in production builds. + */ + if (IS_ENABLED(CONFIG_SLUB_DEBUG) && init && ((unsigned long)size & KASAN_GRANULE_MASK)) { + init = false; + memzero_explicit((void *)addr, size); + } size = round_up(size, KASAN_GRANULE_SIZE); hw_set_mem_tag_range((void *)addr, size, tag, init); -- 2.18.0