[PATCH 5.4 058/154] net: atm: fix use after free in lec_send()

Greg Kroah-Hartman
2025-04-08T12:04:52Z

From: Dan Carpenter <dan.carpenter@linaro.org>

[ Upstream commit f3009d0d6ab78053117f8857b921a8237f4d17b3 ]

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

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/c751531d-4af4-42fe-affe-6104b34b791d@stanley.mountain
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/atm/lec.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/atm/lec.c b/net/atm/lec.c
index 3625a04a6c701..07d4f256c38c1 100644
--- a/net/atm/lec.c
+++ b/net/atm/lec.c
@@ -181,6 +181,7 @@ 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);
@@ -191,7 +192,7 @@ 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)
--
2.39.5