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* [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit
@ 2021-03-29  9:02 Lv Yunlong
  2021-03-29  9:51 ` Heiner Kallweit
  0 siblings, 1 reply; 3+ messages in thread
From: Lv Yunlong @ 2021-03-29  9:02 UTC (permalink / raw)
  To: hkallweit1, nic_swsd, kuba; +Cc: netdev, linux-kernel, Lv Yunlong

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.

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 <lyl2019@mail.ustc.edu.cn>
---
 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;
 
-- 
2.25.1



^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit
  2021-03-29  9:02 [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit Lv Yunlong
@ 2021-03-29  9:51 ` Heiner Kallweit
  2021-03-29 10:11   ` lyl2019
  0 siblings, 1 reply; 3+ messages in thread
From: Heiner Kallweit @ 2021-03-29  9:51 UTC (permalink / raw)
  To: Lv Yunlong, nic_swsd, kuba; +Cc: netdev, linux-kernel

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").


> 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 <lyl2019@mail.ustc.edu.cn>
> ---
>  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;
>  
> 


^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: Re: [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit
  2021-03-29  9:51 ` Heiner Kallweit
@ 2021-03-29 10:11   ` lyl2019
  0 siblings, 0 replies; 3+ messages in thread
From: lyl2019 @ 2021-03-29 10:11 UTC (permalink / raw)
  To: Heiner Kallweit; +Cc: nic_swsd, kuba, netdev, linux-kernel




> -----原始邮件-----
> 发件人: "Heiner Kallweit" <hkallweit1@gmail.com>
> 发送时间: 2021-03-29 17:51:30 (星期一)
> 收件人: "Lv Yunlong" <lyl2019@mail.ustc.edu.cn>, nic_swsd@realtek.com, kuba@kernel.org
> 抄送: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
> 主题: Re: [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit
> 
> 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").
> 
> 
> > 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 <lyl2019@mail.ustc.edu.cn>
> > ---
> >  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;
> >  
> > 
> 

Ok, i see taht __skb_put_padto(skb, padto, false) isn't free skb on error.

Thanks.

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-03-29 10:12 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-29  9:02 [PATCH] ethernet/realtek/r8169: Fix a double free in rtl8169_start_xmit Lv Yunlong
2021-03-29  9:51 ` Heiner Kallweit
2021-03-29 10:11   ` lyl2019

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