linux-kernel - [PATCH AUTOSEL 5.4 23/31] net: appletalk: cops: Fix data race in cops

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Message-Id: <20210603170919.3169112-23-sashal@kernel.org>
Date:   Thu,  3 Jun 2021 13:09:11 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Saubhik Mukherjee <saubhik.mukherjee@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 23/31] net: appletalk: cops: Fix data race in cops_probe1

From: Saubhik Mukherjee <saubhik.mukherjee@...il.com>

[ Upstream commit a4dd4fc6105e54393d637450a11d4cddb5fabc4f ]

In cops_probe1(), there is a write to dev->base_addr after requesting an
interrupt line and registering the interrupt handler cops_interrupt().
The handler might be called in parallel to handle an interrupt.
cops_interrupt() tries to read dev->base_addr leading to a potential
data race. So write to dev->base_addr before calling request_irq().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Saubhik Mukherjee <saubhik.mukherjee@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/appletalk/cops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/appletalk/cops.c b/drivers/net/appletalk/cops.c
index b3c63d2f16aa..5c89c2eff891 100644
--- a/drivers/net/appletalk/cops.c
+++ b/drivers/net/appletalk/cops.c
@@ -325,6 +325,8 @@ static int __init cops_probe1(struct net_device *dev, int ioaddr)
 			break;
 	}
 
+	dev->base_addr = ioaddr;
+
 	/* Reserve any actual interrupt. */
 	if (dev->irq) {
 		retval = request_irq(dev->irq, cops_interrupt, 0, dev->name, dev);
@@ -332,8 +334,6 @@ static int __init cops_probe1(struct net_device *dev, int ioaddr)
 			goto err_out;
 	}
 
-	dev->base_addr = ioaddr;
-
         lp = netdev_priv(dev);
         spin_lock_init(&lp->lock);
 
-- 
2.30.2