[54/90] net: Fix the rollback test in dev_change_name()

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------


From: Eric Dumazet <eric.dumazet@xxxxxxxxx>

[ 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@xxxxxxxxx>
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 net/core/dev.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- 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);
 		}
 	}
 


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