Commit 7418e652 authored by Jia-Ju Bai's avatar Jia-Ju Bai Committed by David S. Miller

isdn: hisax: hfc_pci: Fix a possible concurrency use-after-free bug in HFCPCI_l1hw()

In drivers/isdn/hisax/hfc_pci.c, the functions hfcpci_interrupt() and
HFCPCI_l1hw() may be concurrently executed.

  line 1173: if (!cs->tx_skb)

  line 942: spin_lock_irqsave();
  line 1066: dev_kfree_skb_irq(cs->tx_skb);

Thus, a possible concurrency use-after-free bug may occur
in HFCPCI_l1hw().

To fix these bugs, the calls to spin_lock_irqsave() and
spin_unlock_irqrestore() are added in HFCPCI_l1hw(), to protect the
access to cs->tx_skb.
Signed-off-by: default avatarJia-Ju Bai <>
Signed-off-by: default avatarDavid S. Miller <>
parent f9fc54d3
......@@ -1169,11 +1169,13 @@ HFCPCI_l1hw(struct PStack *st, int pr, void *arg)
if (cs->debug & L1_DEB_LAPD)
debugl1(cs, "-> PH_REQUEST_PULL");
spin_lock_irqsave(&cs->lock, flags);
if (!cs->tx_skb) {
test_and_clear_bit(FLG_L1_PULL_REQ, &st->l1.Flags);
st->l1.l1l2(st, PH_PULL | CONFIRM, NULL);
} else
test_and_set_bit(FLG_L1_PULL_REQ, &st->l1.Flags);
spin_unlock_irqrestore(&cs->lock, flags);
spin_lock_irqsave(&cs->lock, flags);
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