net: Fix skb_under_panic oops in neigh_resolve_output

[ Upstream commit e1f165032c8bade3a6bdf546f8faf61fda4dd01c ]

The retry loop in neigh_resolve_output() and neigh_connected_output()
call dev_hard_header() with out reseting the skb to network_header.
This causes the retry to fail with skb_under_panic. The fix is to
reset the network_header within the retry loop.

Signed-off-by: Ramesh Nagappa <ramesh.nagappa@ericsson.com>
Reviewed-by: Shawn Lu <shawn.lu@ericsson.com>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>
Reviewed-by: Billie Alsup <billie.alsup@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 96bb0a33f86133b29c3f93082bae3987bc6be4bd..eb8857a5e93af2cef3f5c9966cac8a628a0c942b 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1313,8 +1313,6 @@ int neigh_resolve_output(struct sk_buff *skb)
        if (!dst)
                goto discard;
 
-       __skb_pull(skb, skb_network_offset(skb));
-
        if (!neigh_event_send(neigh, skb)) {
                int err;
                struct net_device *dev = neigh->dev;
@@ -1326,6 +1324,7 @@ int neigh_resolve_output(struct sk_buff *skb)
                        neigh_hh_init(neigh, dst, dst->ops->protocol);
 
                do {
+                       __skb_pull(skb, skb_network_offset(skb));
                        seq = read_seqbegin(&neigh->ha_lock);
                        err = dev_hard_header(skb, dev, ntohs(skb->protocol),
                                              neigh->ha, NULL, skb->len);
@@ -1358,9 +1357,8 @@ int neigh_connected_output(struct sk_buff *skb)
        struct net_device *dev = neigh->dev;
        unsigned int seq;
 
-       __skb_pull(skb, skb_network_offset(skb));
-
        do {
+               __skb_pull(skb, skb_network_offset(skb));
                seq = read_seqbegin(&neigh->ha_lock);
                err = dev_hard_header(skb, dev, ntohs(skb->protocol),
                                      neigh->ha, NULL, skb->len);