* [PATCH v2] ath9k: ath9k_htc_rx_msg: return when sk_buff is too small
@ 2021-05-02 21:26 Phillip Potter
2021-05-30 9:00 ` Kalle Valo
0 siblings, 1 reply; 2+ messages in thread
From: Phillip Potter @ 2021-05-02 21:26 UTC (permalink / raw
To: kvalo; +Cc: davem, kuba, linux-wireless, netdev, linux-kernel, ath9k-devel,
fw
At the start of ath9k_htc_rx_msg, we check to see if the skb pointer is
valid, but what we don't do is check if it is large enough to contain a
valid struct htc_frame_hdr. We should check for this and return if not,
as the buffer is invalid in this case. Fixes a KMSAN-found uninit-value bug
reported by syzbot at:
https://syzkaller.appspot.com/bug?id=7dccb7d9ad4251df1c49f370607a49e1f09644ee
Reported-by: syzbot+e4534e8c1c382508312c@syzkaller.appspotmail.com
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
---
V2:
* Free skb properly when this problem is detected, as pointed out by
Florian Westphal.
---
drivers/net/wireless/ath/ath9k/htc_hst.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index 510e61e97dbc..1fe89b068ac4 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -406,6 +406,11 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,
if (!htc_handle || !skb)
return;
+ if (!pskb_may_pull(skb, sizeof(struct htc_frame_hdr))) {
+ kfree_skb(skb);
+ return;
+ }
+
htc_hdr = (struct htc_frame_hdr *) skb->data;
epid = htc_hdr->endpoint_id;
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH v2] ath9k: ath9k_htc_rx_msg: return when sk_buff is too small
2021-05-02 21:26 [PATCH v2] ath9k: ath9k_htc_rx_msg: return when sk_buff is too small Phillip Potter
@ 2021-05-30 9:00 ` Kalle Valo
0 siblings, 0 replies; 2+ messages in thread
From: Kalle Valo @ 2021-05-30 9:00 UTC (permalink / raw
To: Phillip Potter
Cc: davem, kuba, linux-wireless, netdev, linux-kernel, ath9k-devel,
fw
Phillip Potter <phil@philpotter.co.uk> writes:
> At the start of ath9k_htc_rx_msg, we check to see if the skb pointer is
> valid, but what we don't do is check if it is large enough to contain a
> valid struct htc_frame_hdr. We should check for this and return if not,
> as the buffer is invalid in this case. Fixes a KMSAN-found uninit-value bug
> reported by syzbot at:
> https://syzkaller.appspot.com/bug?id=7dccb7d9ad4251df1c49f370607a49e1f09644ee
>
> Reported-by: syzbot+e4534e8c1c382508312c@syzkaller.appspotmail.com
> Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
> ---
>
> V2:
> * Free skb properly when this problem is detected, as pointed out by
> Florian Westphal.
>
> ---
> drivers/net/wireless/ath/ath9k/htc_hst.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
> index 510e61e97dbc..1fe89b068ac4 100644
> --- a/drivers/net/wireless/ath/ath9k/htc_hst.c
> +++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
> @@ -406,6 +406,11 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,
> if (!htc_handle || !skb)
> return;
>
> + if (!pskb_may_pull(skb, sizeof(struct htc_frame_hdr))) {
> + kfree_skb(skb);
> + return;
> + }
This does not look complete to me, I think the function is missing
proper length checks. For example, with ENDPOINT0 it reads two byte
msg_id after the htc header and it's not verified that skb really has
that. I did not check if ep_callbacks.rx handlers have proper length
handling, I recommend verifying that also while fixing this.
Also I want to point out that the skb is freed differently based on
endpoint, I did not check why and don't know if it causes:
if (epid < 0 || epid >= ENDPOINT_MAX) {
if (pipe_id != USB_REG_IN_PIPE)
dev_kfree_skb_any(skb);
else
kfree_skb(skb);
return;
}
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
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2021-05-02 21:26 [PATCH v2] ath9k: ath9k_htc_rx_msg: return when sk_buff is too small Phillip Potter
2021-05-30 9:00 ` Kalle Valo
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