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 2FB1BC433DF for ; Mon, 29 Jun 2020 20:30:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13446206A5 for ; Mon, 29 Jun 2020 20:30:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593462607; bh=bingTPScKkkM0ByjnLCh9QeJkSmQbm0pXupv55UFmYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Z46FJ0N6OVzc6OvURVVTw6BMWhPAoV0LvNPhcOq7E0Mby64DLCm31nq0cz87hOU1N wO8NCTHuVJNstUWSbBYXHPXXqqXADQXJUemZd6CJ392ssvVH2xpUj1DdEB8kr8NJX2 NaRD2watu9kx2+C44NAt3dIl296k9FTQZFEScrqY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389259AbgF2UaD (ORCPT ); Mon, 29 Jun 2020 16:30:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:37066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732496AbgF2TZV (ORCPT ); Mon, 29 Jun 2020 15:25:21 -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 C7AEC25330; Mon, 29 Jun 2020 15:39:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593445168; bh=bingTPScKkkM0ByjnLCh9QeJkSmQbm0pXupv55UFmYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gZbIdrLSkUkKqfNfGEXtVw5bOYh6TVyLwsblGb5xIJA+a3Chn89wxFQ22eLnd6BB6 DGdEBiugFsJVL4ptJZnW3WGEyyyYN7jlK3pa+zDcCpUjHE82+O4Eqa5FLtB5aUV52y x1HaPgSjO1Az6ADDsCcs3EE3oDZukFF+xjE/a4Dk= 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 4.14 64/78] mm/slab: use memzero_explicit() in kzfree() Date: Mon, 29 Jun 2020 11:37:52 -0400 Message-Id: <20200629153806.2494953-65-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629153806.2494953-1-sashal@kernel.org> References: <20200629153806.2494953-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.14.186-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.14.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.14.186-rc1 X-KernelTest-Deadline: 2020-07-01T15:38+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 f6764cf162b8c..caba3efce3f4d 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1449,7 +1449,7 @@ 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