linux-kernel - [PATCH 2/2] usb: ehci: Prevent possible modulo by zero

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Date:   Wed, 24 Aug 2022 00:27:58 +0600
From:   Khalid Masum <khalid.masum.92@...il.com>
To:     Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Khalid Masum <khalid.masum.92@...il.com>
Subject: [PATCH 2/2] usb: ehci: Prevent possible modulo by zero

usb_maxpacket() returns 0 if it fails to fetch the endpoint. This
value is later used for calculating modulo. Which can cause modulo
by zero in qtd_fill.

Prevent this breakage by returning if maxpacket is found to be 0.

Fixes coverity warning: 1487371 ("Division or modulo by zero")
Fixes: 9841f37a1cca ("usb: ehci: Add support for SINGLE_STEP_SET_FEATURE test of EHSET")
Signed-off-by: Khalid Masum <khalid.masum.92@...il.com>
---
 drivers/usb/host/ehci-q.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index eb31d13e9ecd..cf2585e9a09f 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -1221,6 +1221,8 @@ static int ehci_submit_single_step_set_feature(
 	token |= (1 /* "in" */ << 8);  /*This is IN stage*/
 
 	maxpacket = usb_maxpacket(urb->dev, urb->pipe);
+	if (unlikely(!maxpacket))
+		return -1;
 
 	qtd_fill(ehci, qtd, buf, len, token, maxpacket);
 
-- 
2.37.1