2020-03-31 03:30:00

by Qiujun Huang

Subject: [PATCH] ath9k: fix stack-out-of-bounds Write in ath9k_hif_usb_rx_cb

Add barrier to accessing the stack array skb_pool.

Reported-by: [email protected]
Signed-off-by: Qiujun Huang <[email protected]>
---
drivers/net/wireless/ath/ath9k/hif_usb.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index dd0c323..c4a2b72 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -612,6 +612,11 @@ static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev,
hif_dev->remain_skb = nskb;
spin_unlock(&hif_dev->rx_lock);
} else {
+ if (pool_index == MAX_PKT_NUM_IN_TRANSFER) {
+ dev_err(&hif_dev->udev->dev,
+ "ath9k_htc: over RX MAX_PKT_NUM\n");
+ goto err;
+ }
nskb = __dev_alloc_skb(pkt_len + 32, GFP_ATOMIC);
if (!nskb) {
dev_err(&hif_dev->udev->dev,
--
1.8.3.1

2020-03-31 11:04:10

by Kalle Valo

Subject: Re: [PATCH] ath9k: fix stack-out-of-bounds Write in ath9k_hif_usb_rx_cb

Qiujun Huang <[email protected]> writes:

> Add barrier to accessing the stack array skb_pool.
>
> Reported-by: [email protected]
> Signed-off-by: Qiujun Huang <[email protected]>
> ---
> drivers/net/wireless/ath/ath9k/hif_usb.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
> index dd0c323..c4a2b72 100644
> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
> @@ -612,6 +612,11 @@ static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev,
> hif_dev->remain_skb = nskb;
> spin_unlock(&hif_dev->rx_lock);
> } else {
> + if (pool_index == MAX_PKT_NUM_IN_TRANSFER) {
> + dev_err(&hif_dev->udev->dev,
> + "ath9k_htc: over RX MAX_PKT_NUM\n");
> + goto err;
> + }

What about 'pool_index >= MAX_PKT_NUM_IN_TRANSFER' just to be on the
safe side? Ah, but then error handling won't work:

err:
for (i = 0; i < pool_index; i++) {
RX_STAT_ADD(skb_completed_bytes, skb_pool[i]->len);
ath9k_htc_rx_msg(hif_dev->htc_handle, skb_pool[i],
skb_pool[i]->len, USB_WLAN_RX_PIPE);
RX_STAT_INC(skb_completed);
}

Maybe that should use 'min(pool_index, MAX_PKT_NUM_IN_TRANSFER - 1)' or
something? Or maybe it's just overengineerin, dunno.

--
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

2020-03-31 11:22:30

by Qiujun Huang

Subject: Re: [PATCH] ath9k: fix stack-out-of-bounds Write in ath9k_hif_usb_rx_cb

On Tue, Mar 31, 2020 at 7:03 PM Kalle Valo <[email protected]> wrote:
>
> Qiujun Huang <[email protected]> writes:
>
> > Add barrier to accessing the stack array skb_pool.
> >
> > Reported-by: [email protected]
> > Signed-off-by: Qiujun Huang <[email protected]>
> > ---
> > drivers/net/wireless/ath/ath9k/hif_usb.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
> > index dd0c323..c4a2b72 100644
> > --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
> > +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
> > @@ -612,6 +612,11 @@ static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev,
> > hif_dev->remain_skb = nskb;
> > spin_unlock(&hif_dev->rx_lock);
> > } else {
> > + if (pool_index == MAX_PKT_NUM_IN_TRANSFER) {
> > + dev_err(&hif_dev->udev->dev,
> > + "ath9k_htc: over RX MAX_PKT_NUM\n");
> > + goto err;
> > + }
>
> What about 'pool_index >= MAX_PKT_NUM_IN_TRANSFER' just to be on the
> safe side? Ah, but then error handling won't work:

Get that.

>
> err:
> for (i = 0; i < pool_index; i++) {
> RX_STAT_ADD(skb_completed_bytes, skb_pool[i]->len);
> ath9k_htc_rx_msg(hif_dev->htc_handle, skb_pool[i],
> skb_pool[i]->len, USB_WLAN_RX_PIPE);
> RX_STAT_INC(skb_completed);
> }
>
> Maybe that should use 'min(pool_index, MAX_PKT_NUM_IN_TRANSFER - 1)' or
> something? Or maybe it's just overengineerin, dunno.

I will take a deeper look, thanks.

>
> --
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches