From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752748Ab1LTI6D (ORCPT ); Tue, 20 Dec 2011 03:58:03 -0500 Received: from terminus.zytor.com ([198.137.202.10]:52302 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752558Ab1LTI5v (ORCPT ); Tue, 20 Dec 2011 03:57:51 -0500 Date: Tue, 20 Dec 2011 00:57:11 -0800 From: tip-bot for Robert Richter Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, stable@vger.kernel.org, robert.richter@amd.com, oprofile-list@lists.sourceforge.net, akpm@linux-foundation.org, tglx@linutronix.de, mikew@google.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, robert.richter@amd.com, oprofile-list@lists.sourceforge.net, akpm@linux-foundation.org, mikew@google.com, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20111219153830.GH16765@erda.amd.com> References: <20111219153830.GH16765@erda.amd.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] oprofile: Fix uninitialized memory access when writing to writing to oprofilefs Git-Commit-ID: 913050b91eb94f194392dd797b1ff3779f606ac0 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Tue, 20 Dec 2011 00:57:18 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 913050b91eb94f194392dd797b1ff3779f606ac0 Gitweb: http://git.kernel.org/tip/913050b91eb94f194392dd797b1ff3779f606ac0 Author: Robert Richter AuthorDate: Mon, 19 Dec 2011 16:38:30 +0100 Committer: Ingo Molnar CommitDate: Mon, 19 Dec 2011 17:18:43 +0100 oprofile: Fix uninitialized memory access when writing to writing to oprofilefs If oprofilefs_ulong_from_user() is called with count equals zero, *val remains unchanged. Depending on the implementation it might be uninitialized. Change oprofilefs_ulong_from_user()'s interface to return count on success. Thus, we are able to return early if count equals zero which avoids using *val uninitialized. Fixing all users of oprofilefs_ulong_ from_user(). This follows write syscall implementation when count is zero: "If count is zero ... [and if] no errors are detected, 0 will be returned without causing any other effect." (man 2 write) Reported-By: Mike Waychison Signed-off-by: Robert Richter Cc: Andrew Morton Cc: Cc: oprofile-list Link: http://lkml.kernel.org/r/20111219153830.GH16765@erda.amd.com Signed-off-by: Ingo Molnar --- arch/s390/oprofile/init.c | 2 +- drivers/oprofile/oprofile_files.c | 7 ++++--- drivers/oprofile/oprofilefs.c | 11 +++++++++-- 3 files changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c index 6efc18b..bd58b72 100644 --- a/arch/s390/oprofile/init.c +++ b/arch/s390/oprofile/init.c @@ -88,7 +88,7 @@ static ssize_t hwsampler_write(struct file *file, char const __user *buf, return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; if (oprofile_started) diff --git a/drivers/oprofile/oprofile_files.c b/drivers/oprofile/oprofile_files.c index 89f6345..84a208d 100644 --- a/drivers/oprofile/oprofile_files.c +++ b/drivers/oprofile/oprofile_files.c @@ -45,7 +45,7 @@ static ssize_t timeout_write(struct file *file, char const __user *buf, return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_timeout(val); @@ -84,7 +84,7 @@ static ssize_t depth_write(struct file *file, char const __user *buf, size_t cou return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_ulong(&oprofile_backtrace_depth, val); @@ -141,9 +141,10 @@ static ssize_t enable_write(struct file *file, char const __user *buf, size_t co return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; + retval = 0; if (val) retval = oprofile_start(); else diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c index d0de6cc..2f0aa0f 100644 --- a/drivers/oprofile/oprofilefs.c +++ b/drivers/oprofile/oprofilefs.c @@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t cou } +/* + * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains + * unchanged and might be uninitialized. This follows write syscall + * implementation when count is zero: "If count is zero ... [and if] + * no errors are detected, 0 will be returned without causing any + * other effect." (man 2 write) + */ int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count) { char tmpbuf[TMPBUFSIZE]; @@ -79,7 +86,7 @@ int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_ raw_spin_lock_irqsave(&oprofilefs_lock, flags); *val = simple_strtoul(tmpbuf, NULL, 0); raw_spin_unlock_irqrestore(&oprofilefs_lock, flags); - return 0; + return count; } @@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_ return -EINVAL; retval = oprofilefs_ulong_from_user(&value, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_ulong(file->private_data, value);