linux-kernel - [PATCH] firewire: Fix potential use-after-free in fwnet_finish_incoming

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Date:   Wed, 23 Nov 2022 16:15:11 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     <stefanr@...6.in-berlin.de>, <andriy.shevchenko@...ux.intel.com>
CC:     <linux1394-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, YueHaibing <yuehaibing@...wei.com>
Subject: [PATCH] firewire: Fix potential use-after-free in fwnet_finish_incoming_packet()

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

Signed-off-by: YueHaibing <yuehaibing@...wei.com>
---
 drivers/firewire/net.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index af22be84034b..9e19f942a545 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -479,7 +479,7 @@ static int fwnet_finish_incoming_packet(struct net_device *net,
 					struct sk_buff *skb, u16 source_node_id,
 					bool is_broadcast, u16 ether_type)
 {
-	int status;
+	int status, recv_len;
 
 	switch (ether_type) {
 	case ETH_P_ARP:
@@ -533,13 +533,14 @@ static int fwnet_finish_incoming_packet(struct net_device *net,
 		}
 		skb->protocol = protocol;
 	}
+	recv_len = skb->len;
 	status = netif_rx(skb);
 	if (status == NET_RX_DROP) {
 		net->stats.rx_errors++;
 		net->stats.rx_dropped++;
 	} else {
 		net->stats.rx_packets++;
-		net->stats.rx_bytes += skb->len;
+		net->stats.rx_bytes += recv_len;
 	}
 
 	return 0;
-- 
2.17.1