| Message ID | 20210502212611.1818-1-phil@philpotter.co.uk (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | [v2] ath9k: ath9k_htc_rx_msg: return when sk_buff is too small | expand |
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; }
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;
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(+)