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dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=g/XCq9NWjq0Gr+UY22VlyYPjoZ5NbZ/MweDOQtIbIAA=; b=Ao2b3qGSpOnFhe Rzxh84XLXVz9MBYnih+DH4PdpXYFd2FNalNaWnV8YoOaTsf/zGHiEgDxa5IXAcJK01PH3bTg+C0lo kwC3hR2yN/lf3+UxXRndniYIRRnL4tLWoIIEK7qFzVC4uiyCM689I6iXgB3AQIrmyBJligVk4qoLC kXOAz8PTvA+ZqoZKXudERiut6O94Me6dfE30Zamyoxm99B82kpxcaINCUrrwz6f6ZFfcz1Elu4m1V PJa/BM+vzFiG1Y8+eoWBt7Q2PTB3DNX+TeOAybzUfMJfHy7cLcCfaS8MLQ4RUVcJyBXiw4sIgPcml FtGCqA3Kflv8tYXaJw2g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iG4GV-0001Yf-6M; Thu, 03 Oct 2019 16:47:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1iG4GR-0001Xy-JW for linux-mediatek@lists.infradead.org; Thu, 03 Oct 2019 16:47:41 +0000 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 C1E9E2070B; Thu, 3 Oct 2019 16:47:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570121259; bh=/F0eqdyJKABuAv6cUV90z+rRaHqrSXh+R+pUYfvNIeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iKVKmIsP7LVq7LiOD9IFKfVO4UKCSI0+X7w866iGWgkmrywWutgrhQ1JhBm11ggPA 0knkaca88xZgNheSRnClUPLqPjCsm0bar3jKYgQcOZM9A4dMq/Keq2TciSi0/+SHNv Ytzk0yCke5B6Y8MueSqGf5/e5GAxGGVp/iuKEjNY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Subject: [PATCH 5.3 212/344] sched/psi: Correct overly pessimistic size calculation Date: Thu, 3 Oct 2019 17:52:57 +0200 Message-Id: <20191003154601.206292517@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191003154540.062170222@linuxfoundation.org> References: <20191003154540.062170222@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191003_094739_684411_BAFDA4A8 X-CRM114-Status: GOOD ( 11.06 ) X-Spam-Score: -5.0 (-----) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-5.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sasha Levin , wsd_upstream@mediatek.com, Peter Zijlstra , Greg Kroah-Hartman , stable@vger.kernel.org, Miles Chen , linux-mediatek@lists.infradead.org, Thomas Gleixner , Linus Torvalds , Ingo Molnar Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.kernel.org@lists.infradead.org From: Miles Chen [ Upstream commit 4adcdcea717cb2d8436bef00dd689aa5bc76f11b ] When passing a equal or more then 32 bytes long string to psi_write(), psi_write() copies 31 bytes to its buf and overwrites buf[30] with '\0'. Which makes the input string 1 byte shorter than it should be. Fix it by copying sizeof(buf) bytes when nbytes >= sizeof(buf). This does not cause problems in normal use case like: "some 500000 10000000" or "full 500000 10000000" because they are less than 32 bytes in length. /* assuming nbytes == 35 */ char buf[32]; buf_size = min(nbytes, (sizeof(buf) - 1)); /* buf_size = 31 */ if (copy_from_user(buf, user_buf, buf_size)) return -EFAULT; buf[buf_size - 1] = '\0'; /* buf[30] = '\0' */ Before: %cd /proc/pressure/ %echo "123456789|123456789|123456789|1234" > memory [ 22.473497] nbytes=35,buf_size=31 [ 22.473775] 123456789|123456789|123456789| (print 30 chars) %sh: write error: Invalid argument %echo "123456789|123456789|123456789|1" > memory [ 64.916162] nbytes=32,buf_size=31 [ 64.916331] 123456789|123456789|123456789| (print 30 chars) %sh: write error: Invalid argument After: %cd /proc/pressure/ %echo "123456789|123456789|123456789|1234" > memory [ 254.837863] nbytes=35,buf_size=32 [ 254.838541] 123456789|123456789|123456789|1 (print 31 chars) %sh: write error: Invalid argument %echo "123456789|123456789|123456789|1" > memory [ 9965.714935] nbytes=32,buf_size=32 [ 9965.715096] 123456789|123456789|123456789|1 (print 31 chars) %sh: write error: Invalid argument Also remove the superfluous parentheses. Signed-off-by: Miles Chen Cc: Cc: Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190912103452.13281-1-miles.chen@mediatek.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/sched/psi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 6e52b67b420e7..517e3719027e6 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -1198,7 +1198,7 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf, if (static_branch_likely(&psi_disabled)) return -EOPNOTSUPP; - buf_size = min(nbytes, (sizeof(buf) - 1)); + buf_size = min(nbytes, sizeof(buf)); if (copy_from_user(buf, user_buf, buf_size)) return -EFAULT;