[PATCH] net/iavf: check for NULL pointer before dereference

[Bruce Richardson <bruce.richardson@intel.com>]

Static analysis with Coverity flags a possible NULL pointer dereference
of "hdr1" when handling IPv4 or IPv6 fragements in
iavf_fdir_parse_pattern.  This is likely a false positive, since the
flow pattern protocol sequences are checked before this function is
called, so all paths leading to a hdr1 dereference start with an
ethernet protocol, which sets hdr1 to a non-NULL value.

However, this is a rather brittle situation, so to prevent any future
issues if a new set of allowed protocols is added with IP but no
Ethernet matching patterns, add explicit NULL checks for hdr1 before
it's used each time.

Coverity Id: 503768

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 drivers/net/intel/iavf/iavf_fdir.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/intel/iavf/iavf_fdir.c b/drivers/net/intel/iavf/iavf_fdir.c
index 8940132dff..ea620863ca 100644
--- a/drivers/net/intel/iavf/iavf_fdir.c
+++ b/drivers/net/intel/iavf/iavf_fdir.c
@@ -806,6 +806,14 @@ iavf_fdir_parse_pattern(__rte_unused struct iavf_adapter *ad,
 				 * ethertype, if the spec and mask is valid,
 				 * set ethertype into input set.
 				 */
+				/* ETH should be present via pattern pre-validation. */
+				if (hdr1 == NULL) {
+					rte_flow_error_set(error, EINVAL,
+						   RTE_FLOW_ERROR_TYPE_ITEM,
+						   item,
+						   "Missing ETH header before IPv4 fragment.");
+					return -rte_errno;
+				}
 				input_set |= IAVF_INSET_ETHERTYPE;
 				VIRTCHNL_ADD_PROTO_HDR_FIELD_BIT(hdr1, ETH,
 								 ETHERTYPE);
@@ -911,6 +919,14 @@ iavf_fdir_parse_pattern(__rte_unused struct iavf_adapter *ad,
 				 * ethertype, if the spec and mask is valid,
 				 * set ethertype into input set.
 				 */
+				/* ETH should be present via pattern pre-validation. */
+				if (hdr1 == NULL) {
+					rte_flow_error_set(error, EINVAL,
+						   RTE_FLOW_ERROR_TYPE_ITEM,
+						   item,
+						   "Missing ETH header before IPv6 fragment.");
+					return -rte_errno;
+				}
 				input_set |= IAVF_INSET_ETHERTYPE;
 				VIRTCHNL_ADD_PROTO_HDR_FIELD_BIT(hdr1, ETH,
 								 ETHERTYPE);
-- 
2.53.0