Subject: [PATCH 22/25] tun: allow positive return values on dev_get_valid_name() call

From: Julien Gomes <[email-masked]>
Date: Wed, 25 Oct 2017 11:50:50 -0700

[ Upstream commit 5c25f65fd1e42685f7ccd80e0621829c105785d9 ]

If the name argument of dev_get_valid_name() contains "%d", it will try
to assign it a unit number in __dev__alloc_name() and return either the
unit number (>= 0) or an error code (< 0).
Considering positive values as error values prevent tun device creations
relying this mechanism, therefor we should only consider negative values
as errors here.

Signed-off-by: Julien Gomes <[email-masked]>
Acked-by: Cong Wang <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/tun.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a774c827a414..518cbfbc8b65 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1788,7 +1788,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		if (!dev)
 			return -ENOMEM;
 		err = dev_get_valid_name(net, dev, name);
-		if (err)
+		if (err < 0)
 			goto err_free_dev;
 
 		dev_net_set(dev, net);
-- 
2.13.6