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

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.

HFCPCI_l1hw()
  line 1173: if (!cs->tx_skb)

hfcpci_interrupt()
  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 <baijiaju1990@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f9fc54d3

drivers/isdn/hisax/hfc_pci.c

+2 −0
Original line number Diff line number Diff line
@@ -1169,11 +1169,13 @@ HFCPCI_l1hw(struct PStack *st, int pr, void *arg) 
		if (cs->debug & L1_DEB_LAPD)

			debugl1(cs, "-> PH_REQUEST_PULL");

#endif

		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);

		break;

	case (HW_RESET | REQUEST):

		spin_lock_irqsave(&cs->lock, flags);