From: Rodolfo Giometti <giometti@linux.it>
Date: Wed, 11 Nov 2009 22:26:52 +0000 (-0800)
Subject: pps: locking scheme fix up for PPS_GETPARAMS
X-Git-Tag: v2.6.31.7~89
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=073493a20768a109ed1e6e744a2fe88e8bbd2fab;p=thirdparty%2Fkernel%2Fstable.git

pps: locking scheme fix up for PPS_GETPARAMS

commit cbf83cc5a29dba480cf1ba1c5e3417a0d4a31410 upstream.

Userland programs may read/write PPS parameters at same time and these
operations may corrupt PPS data.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Tested-by: Reg Clemens <clemens@dwf.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index fea17e7805e9d..ca5183bdad85f 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -71,9 +71,14 @@ static long pps_cdev_ioctl(struct file *file,
 	case PPS_GETPARAMS:
 		pr_debug("PPS_GETPARAMS: source %d\n", pps->id);
 
-		/* Return current parameters */
-		err = copy_to_user(uarg, &pps->params,
-						sizeof(struct pps_kparams));
+		spin_lock_irq(&pps->lock);
+
+		/* Get the current parameters */
+		params = pps->params;
+
+		spin_unlock_irq(&pps->lock);
+
+		err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
 		if (err)
 			return -EFAULT;