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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 B28CFC433DF for ; Mon, 29 Jun 2020 20:05:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91B052067D for ; Mon, 29 Jun 2020 20:05:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593461133; bh=3LP08SwRXW/pyJM4D6dCQ1NAnxGrOLJBPo7i5vR62t0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=X4JUCbfqeQBqPQYOb4wvOAH/1tkFphFGXoYtzQCzSwmPvNrM2/Jce5Q2BovTWShp4 b8rAhmxJlsISgqseNXDtAKkuL5c6MS/hN24tiKTflrMlBUsqA395j6OGul20D/C01c L0BXIEUQq3Qmef87BiaUWvkb/hsTBRksohEeHhSI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388836AbgF2UFc (ORCPT ); Mon, 29 Jun 2020 16:05:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:40572 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732974AbgF2Ta2 (ORCPT ); Mon, 29 Jun 2020 15:30:28 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B2000252A4; Mon, 29 Jun 2020 15:36:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593445013; bh=3LP08SwRXW/pyJM4D6dCQ1NAnxGrOLJBPo7i5vR62t0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wktRnhAP8C3i1Zc5qQ8C8hOQLJ9lWUe2kyLxBhhfXB2+1srkv1mjj4Vc38wxP1tYp aPkQdiT08BiRbxK/cbfTHc5gFx+LPydr0qqgXVPxmsm5NPN6PsrAQVxxupldxCyDgz QhNa8LE6qmwA/jJLfl+lBH46p5NTlw/SXte2ocIY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Waiman Long , Michal Hocko , David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Joe Perches , Matthew Wilcox , David Rientjes , Johannes Weiner , Dan Carpenter , "Jason A . Donenfeld" , Andrew Morton , Linus Torvalds , Greg Kroah-Hartman Subject: [PATCH 4.19 113/131] mm/slab: use memzero_explicit() in kzfree() Date: Mon, 29 Jun 2020 11:34:44 -0400 Message-Id: <20200629153502.2494656-114-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629153502.2494656-1-sashal@kernel.org> References: <20200629153502.2494656-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.131-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.19.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.19.131-rc1 X-KernelTest-Deadline: 2020-07-01T15:34+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Waiman Long commit 8982ae527fbef170ef298650c15d55a9ccd33973 upstream. 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 buffer clearing. However unlikely, there is still a non-zero probability that the compiler may choose to optimize away the memory clearing especially if LTO is being used in the future. To make sure that this optimization will never happen, memzero_explicit(), which is introduced in v3.18, is now used in kzfree() to future-proof it. Link: http://lkml.kernel.org/r/20200616154311.12314-2-longman@redhat.com Fixes: 3ef0e5ba4673 ("slab: introduce kzfree()") Signed-off-by: Waiman Long Acked-by: Michal Hocko Cc: David Howells Cc: Jarkko Sakkinen Cc: James Morris Cc: "Serge E. Hallyn" Cc: Joe Perches Cc: Matthew Wilcox Cc: David Rientjes Cc: Johannes Weiner Cc: Dan Carpenter Cc: "Jason A . Donenfeld" Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- 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 39e382acb0b86..b5776b1301f0c 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1540,7 +1540,7 @@ 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); -- 2.25.1