[PATCH v3] i40e: Add checking for null for nlmsg_find_attr()

[Natalia Petrova]

The result of nlmsg_find_attr() 'br_spec' is dereferenced in
nla_for_each_nested(), but it can take NULL value in nla_find() function,
which will result in an error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops")
Signed-off-by: Natalia Petrova <n.petrova@xxxxxxxxxx>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>
---
v3: Fixed mailing list.
v2: The remark about the error code by Simon Horman <simon.horman@xxxxxxxxxxxx> 
was taken into account; return value -ENOENT was changed to -EINVAL.
 drivers/net/ethernet/intel/i40e/i40e_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 53d0083e35da..4626d2a1af91 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -13167,6 +13167,8 @@ static int i40e_ndo_bridge_setlink(struct net_device *dev,
 	}
 
 	br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
+	if (!br_spec)
+		return -EINVAL;
 
 	nla_for_each_nested(attr, br_spec, rem) {
 		__u16 mode;
-- 
2.34.1