[PATCH AUTOSEL 4.4 11/15] net: appletalk: cops: Fix data race in cops_probe1

From: Sasha Levin
Date: Thu Jun 03 2021 - 13:19:06 EST


From: Saubhik Mukherjee <saubhik.mukherjee@xxxxxxxxx>

[ 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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 7f2a032c354c..841a5de58c7c 100644
--- a/drivers/net/appletalk/cops.c
+++ b/drivers/net/appletalk/cops.c
@@ -324,6 +324,8 @@ 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);
@@ -331,8 +333,6 @@ 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