From patchwork Tue Jun 16 01:57:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 11606165 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6DD81138C for ; Tue, 16 Jun 2020 01:58:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5634020768 for ; Tue, 16 Jun 2020 01:58:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cmfbCyUD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726387AbgFPB6M (ORCPT ); Mon, 15 Jun 2020 21:58:12 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:27605 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726640AbgFPB6L (ORCPT ); Mon, 15 Jun 2020 21:58:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592272689; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=w0ZJeQQk3EMaWCq5vRe2fLP4T7LhSgQGKZa9FTUZAA4=; b=cmfbCyUDRGwKjLGBejxtzwXYJZpxYp4m4gTqt1HJSocbaTeByL2ZSn3rJ/ux/7hS8NPcJY pDmzv+GqMhAOF/UyMu9ENB1TqV6U+tP0Mht2YLdiU0vgD5MEO3kgZFDGI5G30nsnTYzl6e 3vAL0jFWUiwI5s0OQXwAYyvRhcKeSIM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-271-siDUOdYEMkuGDz0Coifxdg-1; Mon, 15 Jun 2020 21:58:05 -0400 X-MC-Unique: siDUOdYEMkuGDz0Coifxdg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6856710059B7; Tue, 16 Jun 2020 01:58:00 +0000 (UTC) Received: from llong.com (ovpn-117-41.rdu2.redhat.com [10.10.117.41]) by smtp.corp.redhat.com (Postfix) with ESMTP id 45E126ED96; Tue, 16 Jun 2020 01:57:52 +0000 (UTC) From: Waiman Long To: Andrew Morton , David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Linus Torvalds , Joe Perches , Matthew Wilcox , David Rientjes Cc: Michal Hocko , Johannes Weiner , Dan Carpenter , David Sterba , "Jason A . Donenfeld" , linux-mm@kvack.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-pm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-amlogic@lists.infradead.org, linux-mediatek@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-ppp@vger.kernel.org, wireguard@lists.zx2c4.com, linux-wireless@vger.kernel.org, devel@driverdev.osuosl.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fscrypt@vger.kernel.org, ecryptfs@vger.kernel.org, kasan-dev@googlegroups.com, linux-bluetooth@vger.kernel.org, linux-wpan@vger.kernel.org, linux-sctp@vger.kernel.org, linux-nfs@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, Waiman Long , stable@vger.kernel.org Subject: [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree() Date: Mon, 15 Jun 2020 21:57:16 -0400 Message-Id: <20200616015718.7812-2-longman@redhat.com> In-Reply-To: <20200616015718.7812-1-longman@redhat.com> References: <20200616015718.7812-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: The kzfree() function is normally used to clear some sensitive information, like encryption keys, in the buffer before freeing it back to the pool. Memset() is currently used for the buffer clearing. However, it is entirely possible that the compiler may choose to optimize away the memory clearing especially if LTO is being used. To make sure that this optimization will not happen, memzero_explicit(), which is introduced in v3.18, is now used in kzfree() to do the clearing. Fixes: 3ef0e5ba4673 ("slab: introduce kzfree()") Cc: stable@vger.kernel.org Signed-off-by: Waiman Long Acked-by: Michal Hocko --- 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 9e72ba224175..37d48a56431d 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1726,7 +1726,7 @@ void kzfree(const void *p) if (unlikely(ZERO_OR_NULL_PTR(mem))) return; ks = ksize(mem); - memset(mem, 0, ks); + memzero_explicit(mem, ks); kfree(mem); } EXPORT_SYMBOL(kzfree);