This is a note to let you know that I've just added the patch titled mISDN: hfcsusb: don't call dev_kfree_skb/kfree_skb() under spin_lock_irqsave() to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: misdn-hfcsusb-don-t-call-dev_kfree_skb-kfree_skb-und.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3e8a24c23e4d0ec5f079f9f0838bbf453121ba04 Author: Yang Yingliang <yangyingliang@xxxxxxxxxx> Date: Mon Dec 12 16:41:37 2022 +0800 mISDN: hfcsusb: don't call dev_kfree_skb/kfree_skb() under spin_lock_irqsave() [ Upstream commit ddc9648db162eee556edd5222d2808fe33730203 ] It is not allowed to call kfree_skb() or consume_skb() from hardware interrupt context or with hardware interrupts being disabled. It should use dev_kfree_skb_irq() or dev_consume_skb_irq() instead. The difference between them is free reason, dev_kfree_skb_irq() means the SKB is dropped in error and dev_consume_skb_irq() means the SKB is consumed in normal. skb_queue_purge() is called under spin_lock_irqsave() in hfcusb_l2l1D(), kfree_skb() is called in it, to fix this, use skb_queue_splice_init() to move the dch->squeue to a free queue, also enqueue the tx_skb and rx_skb, at last calling __skb_queue_purge() to free the SKBs afer unlock. In tx_iso_complete(), dev_kfree_skb() is called to consume the transmitted SKB, so replace it with dev_consume_skb_irq(). Fixes: 69f52adb2d53 ("mISDN: Add HFC USB driver") Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx> Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c index 1f89378b5623..111a597ef23c 100644 --- a/drivers/isdn/hardware/mISDN/hfcsusb.c +++ b/drivers/isdn/hardware/mISDN/hfcsusb.c @@ -327,20 +327,24 @@ hfcusb_l2l1D(struct mISDNchannel *ch, struct sk_buff *skb) test_and_clear_bit(FLG_L2_ACTIVATED, &dch->Flags); if (hw->protocol == ISDN_P_NT_S0) { + struct sk_buff_head free_queue; + + __skb_queue_head_init(&free_queue); hfcsusb_ph_command(hw, HFC_L1_DEACTIVATE_NT); spin_lock_irqsave(&hw->lock, flags); - skb_queue_purge(&dch->squeue); + skb_queue_splice_init(&dch->squeue, &free_queue); if (dch->tx_skb) { - dev_kfree_skb(dch->tx_skb); + __skb_queue_tail(&free_queue, dch->tx_skb); dch->tx_skb = NULL; } dch->tx_idx = 0; if (dch->rx_skb) { - dev_kfree_skb(dch->rx_skb); + __skb_queue_tail(&free_queue, dch->rx_skb); dch->rx_skb = NULL; } test_and_clear_bit(FLG_TX_BUSY, &dch->Flags); spin_unlock_irqrestore(&hw->lock, flags); + __skb_queue_purge(&free_queue); #ifdef FIXME if (test_and_clear_bit(FLG_L1_BUSY, &dch->Flags)) dchannel_sched_event(&hc->dch, D_CLEARBUSY); @@ -1331,7 +1335,7 @@ tx_iso_complete(struct urb *urb) printk("\n"); } - dev_kfree_skb(tx_skb); + dev_consume_skb_irq(tx_skb); tx_skb = NULL; if (fifo->dch && get_next_dframe(fifo->dch)) tx_skb = fifo->dch->tx_skb;