[Intel-wired-lan] [PATCH] e1000: free skb when returning on -ENOMEM error
Alexander Duyck
alexander.duyck at gmail.com
Thu Oct 22 15:59:27 UTC 2015
On 10/22/2015 08:27 AM, Jason A. Donenfeld wrote:
> eth_skb_pad returns 0 if it was successful, or -ENOMEM if it was not. In
> that case, this function exits early. Some early exits return with
> NETDEV_TX_BUSY, which queues the skb up to be tried again, and so the
> skb should not be freed. Other early exits return with NETDEV_TX_OK,
> like this one, in which case it's imperative that the skb is freed,
> since it is not queued back up. In this case, upon receiving -ENOMEM
> from eth_skb_pad, the function exits early with NETDEV_TX_OK, but
> forgets to free the skb. This patch fixes that.
>
> In a low memory situation, in which the GFP_ATOMIC allocation from
> eth_skb_pad fails, if a network device is transmitting repeatedly, this
> bug could lead to rapidly leaking memory that could only be recovered by
> a reboot or crash.
>
> Signed-off-by: Jason A. Donenfeld <Jason at zx2c4.com>
> ---
> drivers/net/ethernet/intel/e1000/e1000_main.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index 74dc150..0d6b4c8 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -3130,8 +3130,10 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
> * packets may get corrupted during padding by HW.
> * To WA this issue, pad all small packets manually.
> */
> - if (eth_skb_pad(skb))
> + if (eth_skb_pad(skb)) {
> + dev_kfree_skb_any(skb);
> return NETDEV_TX_OK;
> + }
>
> mss = skb_shinfo(skb)->gso_size;
> /* The controller does a simple calculation to
>
This patch makes no sense. The function eth_skb_pad will have freed the
skb if it is returning an error value. As such there is nothing to
free. The code was correct before.
- Alex
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