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SubjectRe: [PATCH] ath9k: fix stack-out-of-bounds Write in ath9k_hif_usb_rx_cb
Date
Qiujun Huang <hqjagain@gmail.com> writes:

> Add barrier to accessing the stack array skb_pool.
>
> Reported-by: syzbot+d403396d4df67ad0bd5f@syzkaller.appspotmail.com
> Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
> ---
> 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

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