[PATCH net] broadcom: b44: prevent uninitialized value usage

[Alexey Simakov <bigalex934@gmail.com>]

On execution path with raised B44_FLAG_EXTERNAL_PHY, b44_readphy()
leaves bmcr value uninitialized and it is used later in the code.

Add check of this flag at the beginning of the b44_nway_reset() and
exit early of the function if an external PHY is used, that would
also correspond to other b44_readphy() call sites.

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

Fixes: 753f492093da ("[B44]: port to native ssb support")
Signed-off-by: Alexey Simakov <bigalex934@gmail.com>
---
 drivers/net/ethernet/broadcom/b44.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/b44.c b/drivers/net/ethernet/broadcom/b44.c
index 0353359c3fe9..cbfd65881326 100644
--- a/drivers/net/ethernet/broadcom/b44.c
+++ b/drivers/net/ethernet/broadcom/b44.c
@@ -1789,6 +1789,9 @@ static int b44_nway_reset(struct net_device *dev)
 	u32 bmcr;
 	int r;
 
+	if (bp->flags & B44_FLAG_EXTERNAL_PHY)
+		return 0;
+
 	spin_lock_irq(&bp->lock);
 	b44_readphy(bp, MII_BMCR, &bmcr);
 	b44_readphy(bp, MII_BMCR, &bmcr);
-- 
2.34.1