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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Haimin Zhang <tcs.kernel@gmail.com>,
        TCS Robot <tcs_robot@tencent.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sasha Levin <sashal@kernel.org>, alcooperx@gmail.com,
        linux-usb@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com
Subject: [PATCH AUTOSEL 5.16 030/217] USB: ehci_brcm_hub_control: Improve port index sanitizing
Date:   Mon, 17 Jan 2022 21:16:33 -0500
Message-Id: <20220118021940.1942199-30-sashal@kernel.org>
In-Reply-To: <20220118021940.1942199-1-sashal@kernel.org>
References: <20220118021940.1942199-1-sashal@kernel.org>
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From: Haimin Zhang <tcs.kernel@gmail.com>

[ Upstream commit 9933698f6119886c110750e67c10ac66f12b730f ]

Due to (wIndex & 0xff) - 1 can get an integer greater than 15, this
can cause array index to be out of bounds since the size of array
port_status is 15. This change prevents a possible out-of-bounds
pointer computation by forcing the use of a valid port number.

Reported-by: TCS Robot <tcs_robot@tencent.com>
Signed-off-by: Haimin Zhang <tcs.kernel@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20211113165320.GA59686@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/host/ehci-brcm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/ehci-brcm.c b/drivers/usb/host/ehci-brcm.c
index d3626bfa966b4..6a0f64c9e5e88 100644
--- a/drivers/usb/host/ehci-brcm.c
+++ b/drivers/usb/host/ehci-brcm.c
@@ -62,8 +62,12 @@ static int ehci_brcm_hub_control(
 	u32 __iomem	*status_reg;
 	unsigned long flags;
 	int retval, irq_disabled = 0;
+	u32 temp;
 
-	status_reg = &ehci->regs->port_status[(wIndex & 0xff) - 1];
+	temp = (wIndex & 0xff) - 1;
+	if (temp >= HCS_N_PORTS_MAX)	/* Avoid index-out-of-bounds warning */
+		temp = 0;
+	status_reg = &ehci->regs->port_status[temp];
 
 	/*
 	 * RESUME is cleared when GetPortStatus() is called 20ms after start
-- 
2.34.1