[PATCH 12/17] net/cnxk: fix unsigned integer underflow in LSO calculation

[Rahul Bhansali]

From: Aarnav JP <ajp at marvell.com>

Replace branchless mask-based selection with a ternary operator
to resolve Coverity integer underflow warning. The expression
-(!w1.il3type) assigned -1 to a uint64_t variable, which is
well-defined but flagged as an unsigned integer underflow.

Coverity issue: 502004

Fixes: 19f3af2371a7 ("net/cnxk: add Tx burst for CN10K")
Fixes: 39dc567c1955 ("net/cnxk: add Tx burst for CN9K")
Fixes: 006c1daa89b9 ("net/cnxk: support Tx burst scalar for CN20K")
Cc: stable at dpdk.org

Signed-off-by: Aarnav JP <ajp at marvell.com>
---
 drivers/net/cnxk/cn10k_tx.h | 8 ++------
 drivers/net/cnxk/cn20k_tx.h | 8 ++------
 drivers/net/cnxk/cn9k_tx.h  | 8 ++------
 3 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/drivers/net/cnxk/cn10k_tx.h b/drivers/net/cnxk/cn10k_tx.h
index 8c912a1f35..d5cb2c3294 100644
--- a/drivers/net/cnxk/cn10k_tx.h
+++ b/drivers/net/cnxk/cn10k_tx.h
@@ -1138,10 +1138,8 @@ cn10k_nix_xmit_prepare(struct cn10k_eth_txq *txq,
 	if (flags & NIX_TX_NEED_EXT_HDR && flags & NIX_TX_OFFLOAD_TSO_F &&
 	    (ol_flags & RTE_MBUF_F_TX_TCP_SEG)) {
 		uint16_t lso_sb;
-		uint64_t mask;
 
-		mask = -(!w1.il3type);
-		lso_sb = (mask & w1.ol4ptr) + (~mask & w1.il4ptr) + m->l4_len;
+		lso_sb = (w1.il3type ? w1.il4ptr : w1.ol4ptr) + m->l4_len;
 
 		send_hdr_ext->w0.lso_sb = lso_sb;
 		send_hdr_ext->w0.lso = 1;
@@ -1766,13 +1764,11 @@ cn10k_nix_prepare_tso(struct rte_mbuf *m, union nix_send_hdr_w1_u *w1,
 		      const uint64_t flags, const uint64_t lso_tun_fmt)
 {
 	uint16_t lso_sb;
-	uint64_t mask;
 
 	if (!(ol_flags & RTE_MBUF_F_TX_TCP_SEG))
 		return;
 
-	mask = -(!w1->il3type);
-	lso_sb = (mask & w1->ol4ptr) + (~mask & w1->il4ptr) + m->l4_len;
+	lso_sb = (w1->il3type ? w1->il4ptr : w1->ol4ptr) + m->l4_len;
 
 	w0->u |= BIT(14);
 	w0->lso_sb = lso_sb;
diff --git a/drivers/net/cnxk/cn20k_tx.h b/drivers/net/cnxk/cn20k_tx.h
index 8e64d2e352..a1c71f2761 100644
--- a/drivers/net/cnxk/cn20k_tx.h
+++ b/drivers/net/cnxk/cn20k_tx.h
@@ -1117,10 +1117,8 @@ cn20k_nix_xmit_prepare(struct cn20k_eth_txq *txq, struct rte_mbuf *m, struct rte
 	if (flags & NIX_TX_NEED_EXT_HDR && flags & NIX_TX_OFFLOAD_TSO_F &&
 	    (ol_flags & RTE_MBUF_F_TX_TCP_SEG)) {
 		uint16_t lso_sb;
-		uint64_t mask;
 
-		mask = -(!w1.il3type);
-		lso_sb = (mask & w1.ol4ptr) + (~mask & w1.il4ptr) + m->l4_len;
+		lso_sb = (w1.il3type ? w1.il4ptr : w1.ol4ptr) + m->l4_len;
 
 		send_hdr_ext->w0.lso_sb = lso_sb;
 		send_hdr_ext->w0.lso = 1;
@@ -1732,13 +1730,11 @@ cn20k_nix_prepare_tso(struct rte_mbuf *m, union nix_send_hdr_w1_u *w1, union nix
 		      uint64_t ol_flags, const uint64_t flags, const uint64_t lso_tun_fmt)
 {
 	uint16_t lso_sb;
-	uint64_t mask;
 
 	if (!(ol_flags & RTE_MBUF_F_TX_TCP_SEG))
 		return;
 
-	mask = -(!w1->il3type);
-	lso_sb = (mask & w1->ol4ptr) + (~mask & w1->il4ptr) + m->l4_len;
+	lso_sb = (w1->il3type ? w1->il4ptr : w1->ol4ptr) + m->l4_len;
 
 	w0->u |= BIT(14);
 	w0->lso_sb = lso_sb;
diff --git a/drivers/net/cnxk/cn9k_tx.h b/drivers/net/cnxk/cn9k_tx.h
index 0ec448e36c..2f9b936d56 100644
--- a/drivers/net/cnxk/cn9k_tx.h
+++ b/drivers/net/cnxk/cn9k_tx.h
@@ -478,10 +478,8 @@ cn9k_nix_xmit_prepare(struct cn9k_eth_txq *txq, struct rte_mbuf *m, struct rte_m
 
 	if (flags & NIX_TX_OFFLOAD_TSO_F && (ol_flags & RTE_MBUF_F_TX_TCP_SEG)) {
 		uint16_t lso_sb;
-		uint64_t mask;
 
-		mask = -(!w1.il3type);
-		lso_sb = (mask & w1.ol4ptr) + (~mask & w1.il4ptr) + m->l4_len;
+		lso_sb = (w1.il3type ? w1.il4ptr : w1.ol4ptr) + m->l4_len;
 
 		send_hdr_ext->w0.lso_sb = lso_sb;
 		send_hdr_ext->w0.lso = 1;
@@ -875,13 +873,11 @@ cn9k_nix_prepare_tso(struct rte_mbuf *m, union nix_send_hdr_w1_u *w1,
 		     uint64_t flags)
 {
 	uint16_t lso_sb;
-	uint64_t mask;
 
 	if (!(ol_flags & RTE_MBUF_F_TX_TCP_SEG))
 		return;
 
-	mask = -(!w1->il3type);
-	lso_sb = (mask & w1->ol4ptr) + (~mask & w1->il4ptr) + m->l4_len;
+	lso_sb = (w1->il3type ? w1->il4ptr : w1->ol4ptr) + m->l4_len;
 
 	w0->u |= BIT(14);
 	w0->lso_sb = lso_sb;
-- 
2.34.1