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SubjectRe: [PATCH net] net: nixge: fix potential memory leak in nixge_start_xmit()
Zhang Changzhong <zhangchangzhong@huawei.com> :
> The nixge_start_xmit() returns NETDEV_TX_OK but does not free skb on two
> error handling cases, which can lead to memory leak.
>
> To fix this, return NETDEV_TX_BUSY in case of nixge_check_tx_bd_space()
> fails and add dev_kfree_skb_any() in case of dma_map_single() fails.

This patch merge two unrelated changes. Please split.

> Fixes: 492caffa8a1a ("net: ethernet: nixge: Add support for National Instruments XGE netdev")
> Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
> ---
> drivers/net/ethernet/ni/nixge.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/ni/nixge.c b/drivers/net/ethernet/ni/nixge.c
> index 19d043b593cc..b9091f9bbc77 100644
> --- a/drivers/net/ethernet/ni/nixge.c
> +++ b/drivers/net/ethernet/ni/nixge.c
> @@ -521,13 +521,15 @@ static netdev_tx_t nixge_start_xmit(struct sk_buff *skb,
> if (nixge_check_tx_bd_space(priv, num_frag)) {
> if (!netif_queue_stopped(ndev))
> netif_stop_queue(ndev);
> - return NETDEV_TX_OK;
> + return NETDEV_TX_BUSY;
> }

The driver should probably check the available room before returning
from hard_start_xmit and turn the check above unlikely().

Btw there is no lock and the Tx completion is irq driven: the driver
is racy. :o(

--
Ueimor

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