4.4-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit 7418e6520f22a2e35815122fa5a53d5bbfa2c10f ]
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: Jia-Ju Bai baijiaju1990@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/isdn/hisax/hfc_pci.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/isdn/hisax/hfc_pci.c b/drivers/isdn/hisax/hfc_pci.c index 90449e1e91e5..1b1453d62fed 100644 --- a/drivers/isdn/hisax/hfc_pci.c +++ b/drivers/isdn/hisax/hfc_pci.c @@ -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);