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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 273DFC54FEE for ; Thu, 27 Feb 2020 14:21:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8B4824656 for ; Thu, 27 Feb 2020 14:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582813317; bh=8dJc3VjqGnWWFG3e8ysCnj4VZcKV3ZJX84/9oq8ZYP8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kPKekY1AEwVPISjQzBUjZIsEpo6FlVy7k97ZMmwypHrWO6oZNQO6xLsWpRsCRprdf 0gSs1wJBrlWioxnVMm1g83bEu/9S9mJnMyERGtvjjddQnB6oBL/wnt7bSF8QerZpwo lxZTHR43u6d+NztteGOovsTQ6rLgGvISopAJK9Eg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389484AbgB0OQU (ORCPT ); Thu, 27 Feb 2020 09:16:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:56208 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389446AbgB0OQL (ORCPT ); Thu, 27 Feb 2020 09:16:11 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8DF802468F; Thu, 27 Feb 2020 14:16:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582812971; bh=8dJc3VjqGnWWFG3e8ysCnj4VZcKV3ZJX84/9oq8ZYP8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jLuz1sE3haEaIvcnw+y+V1safsUnRWq8HGVjjlpptr/snF6IKcmHlYc98FRENsP1L MKlQK4IMEXZxZmOeJKwLtKLQVZv9M6VI7Zl4Ni2NC8wNFkvhbyUZUJ0E2ZOIIldbVT CxJshZJv1FeW4sKtTguP4sURl6o3XWRhoOPqcbV4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Suren Baghdasaryan , "Peter Zijlstra (Intel)" , Ingo Molnar , Johannes Weiner Subject: [PATCH 5.5 086/150] sched/psi: Fix OOB write when writing 0 bytes to PSI files Date: Thu, 27 Feb 2020 14:37:03 +0100 Message-Id: <20200227132245.564108676@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132232.815448360@linuxfoundation.org> References: <20200227132232.815448360@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Suren Baghdasaryan commit 6fcca0fa48118e6d63733eb4644c6cd880c15b8f upstream. Issuing write() with count parameter set to 0 on any file under /proc/pressure/ will cause an OOB write because of the access to buf[buf_size-1] when NUL-termination is performed. Fix this by checking for buf_size to be non-zero. Signed-off-by: Suren Baghdasaryan Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Johannes Weiner Link: https://lkml.kernel.org/r/20200203212216.7076-1-surenb@google.com Signed-off-by: Greg Kroah-Hartman --- kernel/sched/psi.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -1199,6 +1199,9 @@ static ssize_t psi_write(struct file *fi if (static_branch_likely(&psi_disabled)) return -EOPNOTSUPP; + if (!nbytes) + return -EINVAL; + buf_size = min(nbytes, sizeof(buf)); if (copy_from_user(buf, user_buf, buf_size)) return -EFAULT;