net: b44: set pause params only when interface is up

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

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).

---
 drivers/net/ethernet/broadcom/b44.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

index 485d32dda56f..ce370ef641f0 100644
@@ -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

Hi Peter

Please take a read of:

https://docs.kernel.org/process/submitting-patches.html

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html#netdev-faq

This is a networking fix, so please base the patch on net:

https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git

Please include a Fixed: tag indicating when the problem was added.

Also, add a Cc: [email protected], which will cause the patch to be back ported to stable trees, including linux-5.15.

You can use the script scripts/get_maintainer.pl to get a list of Maintainers you should Cc: the patch to.

The code change itself looks reasonable, although Florian should review it.

Thanks
Andrew

Hi Andrew,

I’m sorry, I don’t know, when the problem was added. I only know, that there was no problem with OpenWrt < 23.X. But I don’t know why. Perhaps the behaviour of netifd has changed from 22.X to 23.X.

So I guess, that the problem is there since the creation of b44_set_pauseparam(), but it has never been triggered before.

So what should I do please with the Fixed: tag?

TIA for any hints,

           Peter

It looks like this dates back to the beginning of git. So I guess it should be:

Yes, i came to the same conclusion.

Agreed.

Andrew