commit cbf83cc5a29dba480cf1ba1c5e3417a0d4a31410
author Rodolfo Giometti <giometti@linux.it> Wed Nov 11 14:26:52 2009 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> Thu Nov 12 07:26:00 2009 -0800
tree eb7757638e0a8e5509066eebec053a7bffe0138a
parent 69fd8d24673a8f4f8be5db7f84b5dc9e4ff354c8

pps: locking scheme fix up for PPS_GETPARAMS

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>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/pps/pps.c

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index fea17e7..ca5183b 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -71,9 +71,14 @@
 	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;