From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark gross Subject: Re: [PATCH] PM QoS: Allow parsing of ASCII values Date: Sun, 6 Mar 2011 06:07:14 -0800 Message-ID: <20110306140714.GA2438@gvim.org> References: <20110224161732.GA6512@gvim.org> Reply-To: markgross@thegnar.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Alan Stern Cc: linux-pm@lists.linux-foundation.org, Dan Carpenter , mark gross List-Id: linux-pm@vger.kernel.org On Thu, Feb 24, 2011 at 12:00:35PM -0500, Alan Stern wrote: > On Thu, 24 Feb 2011, mark gross wrote: > > > > How careful do you want to be here? For example, which of the > > > following inputs do you want to accept? > > > > > > 0x1234 > > > abcd1234 > > > abcd123456 > > > abcd123456\n > > > abcd1234567 > > > 1234567890 > > > 1234567890\n > > > 12345678901 > > > > > 0x12345678 > > > 0x12345678\n > > just these 2 are what I had planned to allow after this email thread. > > > > > 0x123456789 > > > > > > Maybe it's okay to be a little relaxed about this, and trust the caller > > > to pass in data that makes sense. > > yeah but is it worth the effort? > > Checking for exactly those two forms really is a lot of effort. You > have to make sure the first two characters are "0x" or "0X", you have > to check that each of the next eight characters is a valid hex digit, > and you have to verify that the 11th character, if present, is a > newline. > > If you can get results that are good enough just by calling > strict_strtoul() without all these checks, it's probably worthwhile. > I just don't want any buffer overrun bugs in code I'm writing. I like the attached thank you for all the really useful input. --mark Signed-off-by: mark gross >>From df199e491c750c529abcfb0e2256f508f1afd061 Mon Sep 17 00:00:00 2001 From: mark gross Date: Sun, 6 Mar 2011 05:45:44 -0800 Subject: [PATCH] correct PM QOS's user mode interface to work with ascii input per what is in the kernel docs. Writing a string to the ABI from user mode comes in 2 flavors. one with and one without a '\n' at the end. this change accepts both. echo 0x12345678 > /dev/cpu_dma_latency and echo -n 0x12345678 > /dev/cpu_dma_latency now both work. --- kernel/pm_qos_params.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c index aeaa7f8..b315446 100644 --- a/kernel/pm_qos_params.c +++ b/kernel/pm_qos_params.c @@ -40,6 +40,7 @@ #include #include #include +#include #include @@ -387,15 +388,15 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, if (count == sizeof(s32)) { if (copy_from_user(&value, buf, sizeof(s32))) return -EFAULT; - } else if (count == 11) { /* len('0x12345678/0') */ - if (copy_from_user(ascii_value, buf, 11)) + } else if (count == 10 || count == 11) { /* '0x12345678' or + '0x12345678/n'*/ + ascii_value[count] = 0; + if (copy_from_user(ascii_value, buf, count)) return -EFAULT; - if (strlen(ascii_value) != 10) + if ((x=strict_strtol(ascii_value, 16, &value)) != 0){ + pr_debug("%s, 0x%x, 0x%x\n",ascii_value, value, x); return -EINVAL; - x = sscanf(ascii_value, "%x", &value); - if (x != 1) - return -EINVAL; - pr_debug("%s, %d, 0x%x\n", ascii_value, x, value); + } } else return -EINVAL; -- 1.7.1