[PATCH 4.9 033/207] ath6kl: fix division by zero in send path

[Greg Kroah-Hartman]

From: Johan Hovold <johan@xxxxxxxxxx>

commit c1b9ca365deae667192be9fe24db244919971234 upstream.

Add the missing endpoint max-packet sanity check to probe() to avoid
division by zero in ath10k_usb_hif_tx_sg() in case a malicious device
has broken descriptors (or when doing descriptor fuzz testing).

Note that USB core will reject URBs submitted for endpoints with zero
wMaxPacketSize but that drivers doing packet-size calculations still
need to handle this (cf. commit 2548288b4fb0 ("USB: Fix: Don't skip
endpoint descriptors with maxpacket=0")).

Fixes: 9cbee358687e ("ath6kl: add full USB support")
Cc: stable@xxxxxxxxxxxxxxx      # 3.5
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211027080819.6675-3-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/wireless/ath/ath6kl/usb.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/net/wireless/ath/ath6kl/usb.c
+++ b/drivers/net/wireless/ath/ath6kl/usb.c
@@ -340,6 +340,11 @@ static int ath6kl_usb_setup_pipe_resourc
 				   le16_to_cpu(endpoint->wMaxPacketSize),
 				   endpoint->bInterval);
 		}
+
+		/* Ignore broken descriptors. */
+		if (usb_endpoint_maxp(endpoint) == 0)
+			continue;
+
 		urbcount = 0;
 
 		pipe_num =