[PATCH v2 net] net: hsr: Fix potential use-after-free

[PATCH v2 net] net: hsr: Fix potential use-after-free

[YueHaibing]

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>
---
v2: correct Fixes tag
---
 net/hsr/hsr_forward.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
index a50429a62f74..56bb27d67a2e 100644
--- 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++;
 	}
-- 
2.17.1

Re: [PATCH v2 net] net: hsr: Fix potential use-after-free

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 25 Nov 2022 15:57:24 +0800 you wrote:
> 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>
> ---
> v2: correct Fixes tag
> 
> [...]

Here is the summary with links:
  - [v2,net] net: hsr: Fix potential use-after-free
    https://git.kernel.org/netdev/net/c/7e177d32442b

You are awesome, thank you!
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