net: Fix the rollback test in dev_change_name()

net: Fix the rollback test in dev_change_name()

In dev_change_name() an err variable is used for storing the original
call_netdevice_notifiers() errno (negative) and testing for a rollback
error later, but the test for non-zero is wrong, because the err might
have positive value as well - from dev_alloc_name(). It means the
rollback for a netdevice with a number > 0 will never happen. (The err
test is reordered btw. to make it more readable.)

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 5 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index b8f74cfb1bfd..fe10551d3671 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -942,14 +942,15 @@ rollback:
         ret = notifier_to_errno(ret);
 
         if (ret) {
-                if (err) {
-                        printk(KERN_ERR
-                               "%s: name change rollback failed: %d.\n",
-                               dev->name, ret);
-                } else {
+                /* err >= 0 after dev_alloc_name() or stores the first errno */
+                if (err >= 0) {
                         err = ret;
                         memcpy(dev->name, oldname, IFNAMSIZ);
                         goto rollback;
+                } else {
+                        printk(KERN_ERR
+                               "%s: name change rollback failed: %d.\n",
+                               dev->name, ret);
                 }
         }