[PATCH 4.9 15/20] staging: gdm724x: fix use after free in gdm_lte_rx()

Greg Kroah-Hartman
2022-03-14T11:35:16Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit fc7f750dc9d102c1ed7bbe4591f991e770c99033 upstream.

The netif_rx_ni() function frees the skb so we can't dereference it to
save the skb->len.

Fixes: 61e121047645 ("staging: gdm7240: adding LTE USB driver")
Cc: stable <stable@vger.kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20220228074331.GA13685@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/staging/gdm724x/gdm_lte.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/staging/gdm724x/gdm_lte.c
+++ b/drivers/staging/gdm724x/gdm_lte.c
@@ -85,14 +85,15 @@ static void tx_complete(void *arg)

static int gdm_lte_rx(struct sk_buff *skb, struct nic *nic, int nic_type)
{
- int ret;
+ int ret, len;

+ len = skb->len + ETH_HLEN;
ret = netif_rx_ni(skb);
if (ret == NET_RX_DROP) {
nic->stats.rx_dropped++;
} else {
nic->stats.rx_packets++;
- nic->stats.rx_bytes += skb->len + ETH_HLEN;
+ nic->stats.rx_bytes += len;
}

return 0;