[PATCH 4.4 42/97] qlcnic: fix unchecked return value

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pan Bian <bianpan2016@xxxxxxx>


[ Upstream commit 91ec701a553cb3de470fd471c6fefe3ad1125455 ]

Function pci_find_ext_capability() may return 0, which is an invalid
address. In function qlcnic_sriov_virtid_fn(), its return value is used
without validation. This may result in invalid memory access bugs. This
patch fixes the bug.

Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_common.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_common.c
+++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_common.c
@@ -127,6 +127,8 @@ static int qlcnic_sriov_virtid_fn(struct
 		return 0;
 
 	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_SRIOV);
+	if (!pos)
+		return 0;
 	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
 	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);