From 49c430106b1094f141323a2aefa1344258806110 Mon Sep 17 00:00:00 2001
From: Maciej Bielski <mba@semihalf.com>
Date: Thu, 1 Aug 2019 13:45:36 +0200
Subject: [PATCH 070/166] net/ena: fix L4 checksum Tx offload

During an if-condition evaluation, a 2-bit flag evaluates to 'true' for
'0x1', '0x2' and '0x3'. Thus, from this perspective these flags are
indistinguishable. To make them distinct, respective bits must be
extracted with a mask and then checked for strict equality.

Specifically here, even if `PKT_TX_UDP_CKSUM` (value '0x3') was set, the
expression `mbuf->ol_flags & PKT_TX_TCP` (the second flag of value
'0x1') is evaluated first and the result is 'true'. In consequence, for
UDP packets the execution flow enters an incorrect branch.

Fixes: 56b8b9b7e5d2 ("net/ena: convert to new Tx offloads API")
Cc: stable@dpdk.org

Reported-by: Eduard Serra <eserra@vmware.com>
Signed-off-by: Maciej Bielski <mba@semihalf.com>
Acked-by: Michal Krawczyk <mk@semihalf.com>
---
 drivers/net/ena/ena_ethdev.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index a6f228c0a1..4bb619a3fc 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -333,12 +333,13 @@ static inline void ena_tx_mbuf_prepare(struct rte_mbuf *mbuf,
 		}
 
 		/* check if L4 checksum is needed */
-		if ((mbuf->ol_flags & PKT_TX_TCP_CKSUM) &&
+		if (((mbuf->ol_flags & PKT_TX_L4_MASK) == PKT_TX_TCP_CKSUM) &&
 		    (queue_offloads & DEV_TX_OFFLOAD_TCP_CKSUM)) {
 			ena_tx_ctx->l4_proto = ENA_ETH_IO_L4_PROTO_TCP;
 			ena_tx_ctx->l4_csum_enable = true;
-		} else if ((mbuf->ol_flags & PKT_TX_UDP_CKSUM) &&
-			   (queue_offloads & DEV_TX_OFFLOAD_UDP_CKSUM)) {
+		} else if (((mbuf->ol_flags & PKT_TX_L4_MASK) ==
+				PKT_TX_UDP_CKSUM) &&
+				(queue_offloads & DEV_TX_OFFLOAD_UDP_CKSUM)) {
 			ena_tx_ctx->l4_proto = ENA_ETH_IO_L4_PROTO_UDP;
 			ena_tx_ctx->l4_csum_enable = true;
 		} else {
-- 
2.25.1

