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 88847C433DF for ; Mon, 29 Jun 2020 22:05:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6362120781 for ; Mon, 29 Jun 2020 22:05:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593468349; bh=Fo58XYYbLg0fR3AnA2QeKF2c5Xegrf9NXglg4qyGSC8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rfmK7bqqDD4xS1/v5R+3w2FPXzHPMFBAIvDpEloIjBvzGLlIocg/pAkUp1qTSAWIO iNnKCykXbjTtDacuMMDbgTYv3+VSmSLQYGsMNtGTpzCNr3jmoSM2xHLjWIzk0d9Bwq Nyrvnh7fM3S3QVXNy19314HNA26+ZEkpOYkK+ixQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388198AbgF2WFh (ORCPT ); Mon, 29 Jun 2020 18:05:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:56762 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726151AbgF2SfT (ORCPT ); Mon, 29 Jun 2020 14:35:19 -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 11381247BB; Mon, 29 Jun 2020 15:21:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593444120; bh=Fo58XYYbLg0fR3AnA2QeKF2c5Xegrf9NXglg4qyGSC8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QQfsjHEp8luhvfypCXXlcjytwztzMcm0KfId9l1dhjl45CmRKg5dEV8nT6AIfnOJB NpjN/fNVv3NaQEehMC55b2xLv22LKes8nofvHY9ACoaEsFIQImPH7+k8NI0LqYha9Y k5oM4nhBARToeYZw4NXhZz965kP07Eg3gfTDfzVE= 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 5.7 230/265] mm/slab: use memzero_explicit() in kzfree() Date: Mon, 29 Jun 2020 11:17:43 -0400 Message-Id: <20200629151818.2493727-231-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629151818.2493727-1-sashal@kernel.org> References: <20200629151818.2493727-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.7.7-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.7.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.7.7-rc1 X-KernelTest-Deadline: 2020-07-01T15:14+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 9e72ba2241750..37d48a56431d0 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); -- 2.25.1