[PATCH v2 1/3] ath10k: fix division by zero in send path

From: Johan Hovold
Date: Wed Oct 27 2021 - 04:12:31 EST


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: 4db66499df91 ("ath10k: add initial USB support")
Cc: stable@xxxxxxxxxxxxxxx # 4.14
Cc: Erik Stromdahl <erik.stromdahl@xxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/net/wireless/ath/ath10k/usb.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath10k/usb.c b/drivers/net/wireless/ath/ath10k/usb.c
index 6d831b098cbb..3d98f19c6ec8 100644
--- a/drivers/net/wireless/ath/ath10k/usb.c
+++ b/drivers/net/wireless/ath/ath10k/usb.c
@@ -853,6 +853,11 @@ static int ath10k_usb_setup_pipe_resources(struct ath10k *ar,
le16_to_cpu(endpoint->wMaxPacketSize),
endpoint->bInterval);
}
+
+ /* Ignore broken descriptors. */
+ if (usb_endpoint_maxp(endpoint) == 0)
+ continue;
+
urbcount = 0;

pipe_num =
--
2.32.0