From: Esben Haabendal Date: Fri, 18 Jun 2021 10:52:23 +0000 (+0200) Subject: net: ll_temac: Make sure to free skb when it is completely used X-Git-Tag: v5.13-rc7~8^2~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6aa32217a9a446275440ee8724b1ecaf1838df47;p=thirdparty%2Fkernel%2Flinux.git net: ll_temac: Make sure to free skb when it is completely used With the skb pointer piggy-backed on the TX BD, we have a simple and efficient way to free the skb buffer when the frame has been transmitted. But in order to avoid freeing the skb while there are still fragments from the skb in use, we need to piggy-back on the TX BD of the skb, not the first. Without this, we are doing use-after-free on the DMA side, when the first BD of a multi TX BD packet is seen as completed in xmit_done, and the remaining BDs are still being processed. Cc: stable@vger.kernel.org # v5.4+ Signed-off-by: Esben Haabendal Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c index a1f5f07f4ca97..e82f162cd80c6 100644 --- a/drivers/net/ethernet/xilinx/ll_temac_main.c +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -876,7 +876,6 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev) return NETDEV_TX_OK; } cur_p->phys = cpu_to_be32(skb_dma_addr); - ptr_to_txbd((void *)skb, cur_p); for (ii = 0; ii < num_frag; ii++) { if (++lp->tx_bd_tail >= lp->tx_bd_num) @@ -915,6 +914,11 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev) } cur_p->app0 |= cpu_to_be32(STS_CTRL_APP0_EOP); + /* Mark last fragment with skb address, so it can be consumed + * in temac_start_xmit_done() + */ + ptr_to_txbd((void *)skb, cur_p); + tail_p = lp->tx_bd_p + sizeof(*lp->tx_bd_v) * lp->tx_bd_tail; lp->tx_bd_tail++; if (lp->tx_bd_tail >= lp->tx_bd_num)