net: Fix the rollback test in dev_change_name()

[ Upstream commit 91e9c07bd635353d1a278bdb38dbb56ac371bcb8 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/core/dev.c b/net/core/dev.c
index a2f575b5b0512769759879ce08d7f45c502b4bf3..1bb5f4a8c217d6bde53fdfd7c3585caefdb07544 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -933,14 +933,15 @@ 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);
                }
        }