From: Pan Bian <bianpan2016@xxxxxxx> commit b7aa39a2ed0112d07fc277ebd24a08a7b2368ab9 upstream. The variable skb is released via kfree_skb() when the return value of _rtl92e_tx is not zero. However, after that, skb is accessed again to read its length, which may result in a use after free bug. This patch fixes the bug by moving the release operation to where skb is never used later. Signed-off-by: Pan Bian <bianpan2016@xxxxxxx> Reviewed-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/1572965351-6745-1-git-send-email-bianpan2016@xxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/staging/rtl8192e/rtl8192e/rtl_core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/staging/rtl8192e/rtl8192e/rtl_core.c +++ b/drivers/staging/rtl8192e/rtl8192e/rtl_core.c @@ -1631,14 +1631,15 @@ static void _rtl92e_hard_data_xmit(struc memcpy((unsigned char *)(skb->cb), &dev, sizeof(dev)); skb_push(skb, priv->rtllib->tx_headroom); ret = _rtl92e_tx(dev, skb); - if (ret != 0) - kfree_skb(skb); if (queue_index != MGNT_QUEUE) { priv->rtllib->stats.tx_bytes += (skb->len - priv->rtllib->tx_headroom); priv->rtllib->stats.tx_packets++; } + + if (ret != 0) + kfree_skb(skb); } static int _rtl92e_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
