From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756315Ab2ACWlZ (ORCPT ); Tue, 3 Jan 2012 17:41:25 -0500 Received: from cantor2.suse.de ([195.135.220.15]:40364 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756261Ab2ACWlT (ORCPT ); Tue, 3 Jan 2012 17:41:19 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Tue Jan 3 14:33:23 2012 Message-Id: <20120103223323.009595271@clark.kroah.org> User-Agent: quilt/0.50-25.1 Date: Tue, 03 Jan 2012 14:32:57 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Robert Richter , oprofile-list , Ingo Molnar Subject: [24/75] oprofile: Fix uninitialized memory access when writing to writing to oprofilefs In-Reply-To: <20120103223332.GA4112@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Robert Richter commit 913050b91eb94f194392dd797b1ff3779f606ac0 upstream. 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: oprofile-list Link: http://lkml.kernel.org/r/20111219153830.GH16765@erda.amd.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/s390/oprofile/init.c | 2 +- drivers/oprofile/oprofile_files.c | 7 ++++--- drivers/oprofile/oprofilefs.c | 11 +++++++++-- 3 files changed, 14 insertions(+), 6 deletions(-) --- a/arch/s390/oprofile/init.c +++ b/arch/s390/oprofile/init.c @@ -88,7 +88,7 @@ static ssize_t hwsampler_write(struct fi return -EINVAL; retval = oprofilefs_ulong_from_user(&val, buf, count); - if (retval) + if (retval <= 0) return retval; if (oprofile_started) --- a/drivers/oprofile/oprofile_files.c +++ b/drivers/oprofile/oprofile_files.c @@ -45,7 +45,7 @@ static ssize_t timeout_write(struct file 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 * 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 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 --- a/drivers/oprofile/oprofilefs.c +++ b/drivers/oprofile/oprofilefs.c @@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigne } +/* + * 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 spin_lock_irqsave(&oprofilefs_lock, flags); *val = simple_strtoul(tmpbuf, NULL, 0); spin_unlock_irqrestore(&oprofilefs_lock, flags); - return 0; + return count; } @@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct f 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);