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=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 1A545C433E0 for ; Mon, 29 Jun 2020 18:55:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E707220656 for ; Mon, 29 Jun 2020 18:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593456924; bh=NzJiSt9g1A0IkY1gDVeVFO1A+AGElzRZS2z5eg2GhWk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2tktfvkSd0EYkEgEtajtmabLnW51ebv//kdLuBCc+xAHyrqkMR3ykAxCjB/qWkR6n AWZFEMW5A1gIotF2kgrir9BQu9TA0P3tsQqEpvLdt2N/8bnO+RuIoibt/M75MlyZSX SAhAT0LBCtCjrAROkcWXtZNff8mkADqmKquuNDm0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729996AbgF2SzV (ORCPT ); Mon, 29 Jun 2020 14:55:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:42432 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729943AbgF2SzQ (ORCPT ); Mon, 29 Jun 2020 14:55:16 -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 CABCC2556D; Mon, 29 Jun 2020 15:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593446132; bh=NzJiSt9g1A0IkY1gDVeVFO1A+AGElzRZS2z5eg2GhWk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bJinHi6L2hle1kHSTGQADdjxYiHX9z9DjaHCQ1Ljttb0U1vrEWpQeDShfdjrOLQNN 012Y8oZU0lTl6CNC6Miq7ujGNxxKxG/knWiMTUeZhP8eJ5LDPYxnmqMcJI1Iqvc5Fk Q+WoaNVUgkeisnHNvaocP4RDshpNcUeg5KbP+/s0= 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 4.4 122/135] mm/slab: use memzero_explicit() in kzfree() Date: Mon, 29 Jun 2020 11:52:56 -0400 Message-Id: <20200629155309.2495516-123-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629155309.2495516-1-sashal@kernel.org> References: <20200629155309.2495516-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.4.229-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.4.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.4.229-rc1 X-KernelTest-Deadline: 2020-07-01T15:53+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 01e7246de8dfa..5d8c809a3ff71 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1269,7 +1269,7 @@ 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