2021-03-29 11:01:59

by Lv Yunlong

Subject: [PATCH] wireless: hostap: Fix a use after free in hostap_80211_rx

Function hostap_80211_rx() calls prism2_rx_80211(..,skb,..). In
prism2_rx_80211, i found that the skb could be freed by dev_kfree_skb_any(skb)
and return 0. Also could be freed by netif_rx(skb) when netif_rx return
NET_RX_DROP.

But after called the prism2_rx_80211(..,skb,..), the skb is used by skb->len.

As the new skb->len is returned by prism2_rx_80211(), my patch uses a variable
len to repalce skb->len. According to another useage of prism2_rx_80211 in
monitor_rx().

Signed-off-by: Lv Yunlong <[email protected]>
---
drivers/net/wireless/intersil/hostap/hostap_80211_rx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intersil/hostap/hostap_80211_rx.c b/drivers/net/wireless/intersil/hostap/hostap_80211_rx.c
index 61be822f90b5..a45ee7b35533 100644
--- a/drivers/net/wireless/intersil/hostap/hostap_80211_rx.c
+++ b/drivers/net/wireless/intersil/hostap/hostap_80211_rx.c
@@ -1016,10 +1016,10 @@ void hostap_80211_rx(struct net_device *dev, struct sk_buff *skb,
if (local->hostapd && local->apdev) {
/* Send IEEE 802.1X frames to the user
* space daemon for processing */
- prism2_rx_80211(local->apdev, skb, rx_stats,
+ int len = prism2_rx_80211(local->apdev, skb, rx_stats,
PRISM2_RX_MGMT);
local->apdevstats.rx_packets++;
- local->apdevstats.rx_bytes += skb->len;
+ local->apdevstats.rx_bytes += len;
goto rx_exit;
}
} else if (!frame_authorized) {
--
2.25.1

2021-06-24 16:44:35

by Kalle Valo

Subject: Re: [PATCH] wireless: hostap: Fix a use after free in hostap_80211_rx

Lv Yunlong <[email protected]> wrote:

> Function hostap_80211_rx() calls prism2_rx_80211(..,skb,..). In
> prism2_rx_80211, i found that the skb could be freed by dev_kfree_skb_any(skb)
> and return 0. Also could be freed by netif_rx(skb) when netif_rx return
> NET_RX_DROP.
>
> But after called the prism2_rx_80211(..,skb,..), the skb is used by skb->len.
>
> As the new skb->len is returned by prism2_rx_80211(), my patch uses a variable
> len to repalce skb->len. According to another useage of prism2_rx_80211 in
> monitor_rx().
>
> Signed-off-by: Lv Yunlong <[email protected]>

Can someone help with reviewing the patch?

--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/

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