net: atm: fix use after free in lec_send()

jira VULN-56262
cve CVE-2025-22004
commit-author Dan Carpenter <[email protected]>
commit f3009d0

The ->send() operation frees skb so save the length before calling
->send() to avoid a use after free.

Fixes: 1da177e ("Linux-2.6.12-rc2")
	Signed-off-by: Dan Carpenter <[email protected]>
	Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
	Signed-off-by: Paolo Abeni <[email protected]>

(cherry picked from commit f3009d0)
	Signed-off-by: Pratham Patel <[email protected]>

Author: thefossguy-ciq

net/atm/lec.c

@@ -180,6 +180,7 @@ static void
 lec_send(struct atm_vcc *vcc, struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
+	unsigned int len = skb->len;
 
 	ATM_SKB(skb)->vcc = vcc;
 	atm_account_tx(vcc, skb);
@@ -190,7 +191,7 @@ lec_send(struct atm_vcc *vcc, struct sk_buff *skb)
 	}
 
 	dev->stats.tx_packets++;
-	dev->stats.tx_bytes += skb->len;
+	dev->stats.tx_bytes += len;
 }
 
 static void lec_tx_timeout(struct net_device *dev, unsigned int txqueue)