From a006acb931317aad3a8dd41333ebb0453caf49b8 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 27 Oct 2021 10:08:17 +0200
Subject: [PATCH] ath10k: fix division by zero in send path
Git-commit: a006acb931317aad3a8dd41333ebb0453caf49b8
References: git-fixes
Patch-mainline: v5.16-rc1

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@vger.kernel.org      # 4.14
Cc: Erik Stromdahl <erik.stromdahl@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211027080819.6675-2-johan@kernel.org
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 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 =
-- 
2.40.0