Re: [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: 2021-03-29 09:52:41
Also in:
lkml
On 29.03.2021 11:02, Lv Yunlong wrote:
In rtl8169_start_xmit, it calls rtl8169_tso_csum_v2(tp, skb, opts) and rtl8169_tso_csum_v2() calls __skb_put_padto(skb, padto, false). If __skb_put_padto() failed, it will free the skb in the first time and return error. Then rtl8169_start_xmit will goto err_dma_0.
No, the skb isn't freed here in case of error. Have a look at the
implementation of __skb_put_padto() and see also cc6528bc9a0c
("r8169: fix potential skb double free in an error path").
quoted hunk ↗ jump to hunk
But in err_dma_0 label, the skb is freed by dev_kfree_skb_any(skb) in the second time. My patch adds a new label inside the old err_dma_0 label to avoid the double free and renames the error labels to keep the origin function unchanged. Fixes: b8447abc4c8fb ("r8169: factor out rtl8169_tx_map") Signed-off-by: Lv Yunlong <redacted> --- drivers/net/ethernet/realtek/r8169_main.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c index f704da3f214c..91c43399712b 100644 --- a/drivers/net/ethernet/realtek/r8169_main.c +++ b/drivers/net/ethernet/realtek/r8169_main.c@@ -4217,13 +4217,13 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, if (unlikely(rtl8169_tx_map(tp, opts, skb_headlen(skb), skb->data, entry, false))) - goto err_dma_0; + goto err_dma_1; txd_first = tp->TxDescArray + entry; if (frags) { if (rtl8169_xmit_frags(tp, skb, opts, entry)) - goto err_dma_1; + goto err_dma_2; entry = (entry + frags) % NUM_TX_DESC; }@@ -4270,10 +4270,11 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, return NETDEV_TX_OK; -err_dma_1: +err_dma_2: rtl8169_unmap_tx_skb(tp, entry); -err_dma_0: +err_dma_1: dev_kfree_skb_any(skb); +err_dma_0: dev->stats.tx_dropped++; return NETDEV_TX_OK;