net: hsr: Fix potential use-after-free

The skb is delivered to netif_rx() which may free it, after calling this,
dereferencing skb may trigger use-after-free.

Fixes: f421436a591d ("net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20221125075724.27912-1-yuehaibing@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
index a50429a..56bb27d 100644 (file)
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -351,17 +351,18 @@ static void hsr_deliver_master(struct sk_buff *skb, struct net_device *dev,
                               struct hsr_node *node_src)
 {
        bool was_multicast_frame;
-       int res;
+       int res, recv_len;
 
        was_multicast_frame = (skb->pkt_type == PACKET_MULTICAST);
        hsr_addr_subst_source(node_src, skb);
        skb_pull(skb, ETH_HLEN);
+       recv_len = skb->len;
        res = netif_rx(skb);
        if (res == NET_RX_DROP) {
                dev->stats.rx_dropped++;
        } else {
                dev->stats.rx_packets++;
-               dev->stats.rx_bytes += skb->len;
+               dev->stats.rx_bytes += recv_len;
                if (was_multicast_frame)
                        dev->stats.multicast++;
        }