[PATCH net] net: b44: set pause params only when interface is up

["Peter Münster" <pm@a16n.net>]

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Hi,

This patch fixes a kernel panic when using netifd.
Could you please apply it to linux-5.15.y?

TIA and kind regards,
-- 
           Peter

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b44_free_rings() accesses b44::rx_buffers (and ::tx_buffers)
unconditionally, but b44::rx_buffers is only valid when the
device is up (they get allocated in b44_open(), and deallocated
again in b44_close()), any other time these is just a NULL pointers.

So if you try to change the pause params while the network interface
is disabled/administratively down, everything explodes (which likely
netifd tries to do).

Link: https://github.com/openwrt/openwrt/issues/13789
Reported-by: Peter Münster <pm@a16n.net>
Suggested-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Vaclav Svoboda <svoboda@neng.cz>
Tested-by: Peter Münster <pm@a16n.net>
Signed-off-by: Peter Münster <pm@a16n.net>
---
 drivers/net/ethernet/broadcom/b44.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/b44.c b/drivers/net/ethernet/broadcom/b44.c
index 485d32dda56f..ce370ef641f0 100644
--- a/drivers/net/ethernet/broadcom/b44.c
+++ b/drivers/net/ethernet/broadcom/b44.c
@@ -2029,12 +2029,14 @@ static int b44_set_pauseparam(struct net_device *dev,
 		bp->flags |= B44_FLAG_TX_PAUSE;
 	else
 		bp->flags &= ~B44_FLAG_TX_PAUSE;
-	if (bp->flags & B44_FLAG_PAUSE_AUTO) {
-		b44_halt(bp);
-		b44_init_rings(bp);
-		b44_init_hw(bp, B44_FULL_RESET);
-	} else {
-		__b44_set_flow_ctrl(bp, bp->flags);
+	if (netif_running(dev)) {
+		if (bp->flags & B44_FLAG_PAUSE_AUTO) {
+			b44_halt(bp);
+			b44_init_rings(bp);
+			b44_init_hw(bp, B44_FULL_RESET);
+		} else {
+			__b44_set_flow_ctrl(bp, bp->flags);
+		}
 	}
 	spin_unlock_irq(&bp->lock);
 
-- 
2.35.3


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