linux-kernel - [PATCH] usb: c67x00 - fix potential division by zero in c67x00_end_of

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Message-ID: <20251006140631.1406643-1-Pavel.Zhigulin@kaspersky.com>
Date: Mon, 6 Oct 2025 17:06:30 +0300
From: Pavel Zhigulin <Pavel.Zhigulin@...persky.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: Pavel Zhigulin <Pavel.Zhigulin@...persky.com>, Peter Korsgaard
	<jacmet@...site.dk>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>
Subject: [PATCH] usb: c67x00 - fix potential division by zero in c67x00_end_of_data()

The function 'usb_maxpacket' relies on the value of 'epd->wMaxPacketSize',
which can be zero if the device reports itself as an eUSB2 device
(see 'usb_parse_endpoint' in drivers/usb/core/config.c). Under normal
conditions everything works correctly, but if a broken or malformed
device is handled by this module, a division by zero may occur.

Fix the division by zero by checking the result of the 'usb_maxpacket'
call.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: e9b29ffc519b ("USB: add Cypress c67x00 OTG controller HCD driver")
Signed-off-by: Pavel Zhigulin <Pavel.Zhigulin@...persky.com>
---
 drivers/usb/c67x00/c67x00-sched.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/c67x00/c67x00-sched.c b/drivers/usb/c67x00/c67x00-sched.c
index a09fa68a6ce7..3211843497cc 100644
--- a/drivers/usb/c67x00/c67x00-sched.c
+++ b/drivers/usb/c67x00/c67x00-sched.c
@@ -868,6 +868,9 @@ static inline int c67x00_end_of_data(struct c67x00_td *td)

 	maxps = usb_maxpacket(td_udev(td), td->pipe);

+	if (unlikely(!maxps))
+		return 1;
+
 	if (unlikely(act_bytes < maxps))
 		return 1;	/* Smaller then full packet */

--
2.43.0