From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751339AbVK2HRY (ORCPT ); Tue, 29 Nov 2005 02:17:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751341AbVK2HRY (ORCPT ); Tue, 29 Nov 2005 02:17:24 -0500 Received: from nproxy.gmail.com ([64.233.182.202]:11463 "EHLO nproxy.gmail.com") by vger.kernel.org with ESMTP id S1751339AbVK2HRY convert rfc822-to-8bit (ORCPT ); Tue, 29 Nov 2005 02:17:24 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=Pc/I3KIiLe2CoLQZbTU06aJxx6OhjH4BkVBtJrlne87trs8UgHU1z3CE9mGdH/2BzVSGiUHPjifrf8a3UR1dN4FXETthKMmLv2559MlKQBaPJTdy3RP7l6W2TVVc8Qs9h+ZHfTvNJDswuVw3UxPuFU2//ih1rK8d6fNh7XXlp9k= Message-ID: <121a28810511282317j47a90f6t@mail.gmail.com> Date: Tue, 29 Nov 2005 08:17:22 +0100 From: Grzegorz Nosek To: linux-kernel@vger.kernel.org Subject: [PATCH] race condition in procfs MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, I found a race condition in procfs on SMP systems. The result is an oops in processes like pidof. Apparently ->proc_read() gets passed a potentially NULL pointer. The following micro-patch seems to fix it. Best regards, Grzegorz Nosek --- linux-2.6/fs/proc/base.c.orig 2005-11-25 00:07:43.000000000 +0100 +++ linux-2.6/fs/proc/base.c 2005-11-28 11:44:11.000000000 +0100 @@ -718,6 +718,9 @@ ssize_t length; struct task_struct *task = proc_task(inode); + if (!task) + return -ENOENT; + if (count > PROC_BLOCK_SIZE) count = PROC_BLOCK_SIZE; if (!(page = __get_free_page(GFP_KERNEL)))