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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 7aafaeddfcbffcfc5dcf6bc444600e7f1b429a08..5b9709f18a64c69b3930a14b790de3d78b18f729 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1254,8 +1254,6 @@ int neigh_resolve_output(struct neighbour *neigh, 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;
@@ -1265,6 +1263,7 @@ int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb)
                        neigh_hh_init(neigh, dst);
 
                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);
@@ -1295,9 +1294,8 @@ int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb)
        unsigned int seq;
        int err;
 
-       __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);