netdev - [PATCH net 4/5] ppp: protect access to ppp->last_{xmit,recv} in ppp

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Message-ID: <6778ebf050f00363ef5f4edfc53b7f905201abd5.1456167043.git.g.nault@alphalink.fr>
Date:	Mon, 22 Feb 2016 20:47:19 +0100
From:	Guillaume Nault <g.nault@...halink.fr>
To:	netdev@...r.kernel.org
Cc:	Paul Mackerras <paulus@...ba.org>,
	David Miller <davem@...emloft.net>
Subject: [PATCH net 4/5] ppp: protect access to ppp->last_{xmit,recv} in
 ppp_ioctl()

ppp->last_xmit is witten to by ppp_send_frame() while protected by
ppp_xmit_lock().
Likewise, ppp->last_recv is written to by ppp_receive_nonmp_frame()
while protected by ppp_recv_lock().

Holding both locks is therefore necessary before ppp_ioctl() can safely
read these fields.

Signed-off-by: Guillaume Nault <g.nault@...halink.fr>
---
 drivers/net/ppp/ppp_generic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 183d89c..24777f4 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -726,8 +726,11 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		break;
 
 	case PPPIOCGIDLE:
+		ppp_lock(ppp);
 		idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
 		idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
+		ppp_unlock(ppp);
+
 		if (copy_to_user(argp, &idle, sizeof(idle)))
 			break;
 		err = 0;
-- 
2.7.0