[PATCH 4.9 22/39] tun: allow positive return values on dev_get_valid_name() call

From: Greg Kroah-Hartman
Date: Thu Nov 16 2017 - 13:07:39 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Julien Gomes <julien@xxxxxxxxxx>

[ 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 <julien@xxxxxxxxxx>
Acked-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/tun.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1788,7 +1788,7 @@ static int tun_set_iff(struct net *net,
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);