From db6c3c064f5d55fa9969f33eafca3cdbefbb3541 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Tue, 26 Oct 2021 12:36:17 +0200
Subject: [PATCH] net: lan78xx: fix division by zero in send path
Git-commit: db6c3c064f5d55fa9969f33eafca3cdbefbb3541
References: git-fixes
Patch-mainline: v5.15
Add the missing endpoint max-packet sanity check to probe() to avoid
division by zero in lan78xx_tx_bh() 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: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
Cc: stable@vger.kernel.org # 4.3
Cc: Woojung.Huh@microchip.com <Woojung.Huh@microchip.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/net/usb/lan78xx.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 793f8fbe0069..63cd72c5f580 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -4122,6 +4122,12 @@ static int lan78xx_probe(struct usb_interface *intf,
dev->maxpacket = usb_maxpacket(dev->udev, dev->pipe_out, 1);
+ /* Reject broken descriptors. */
+ if (dev->maxpacket == 0) {
+ ret = -ENODEV;
+ goto out4;
+ }
+
/* driver requires remote-wakeup capability during autosuspend. */
intf->needs_remote_wakeup = 1;
--
2.26.2