netdev - [PATCH net-next] ppp: clean up endianness conversions

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Message-Id: <20210107143956.25549-1-jwi@linux.ibm.com>
Date:   Thu,  7 Jan 2021 15:39:56 +0100
From:   Julian Wiedmann <jwi@...ux.ibm.com>
To:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     linux-netdev <netdev@...r.kernel.org>,
        Julian Wiedmann <jwi@...ux.ibm.com>,
        Dmitry Kozlov <xeb@...l.ru>
Subject: [PATCH net-next] ppp: clean up endianness conversions

sparse complains about some harmless endianness issues:

> drivers/net/ppp/pptp.c:281:21: warning: incorrect type in assignment (different base types)
> drivers/net/ppp/pptp.c:281:21:    expected unsigned int [usertype] ack
> drivers/net/ppp/pptp.c:281:21:    got restricted __be32
> drivers/net/ppp/pptp.c:283:23: warning: cast to restricted __be32

Here 'ack' is assigned a value in network-order, and then also the
byte-swapped value in host-order. Clean this up by doing the byte-swap
as part of the assignment.

> drivers/net/ppp/pptp.c:358:26: warning: cast from restricted __be16
> drivers/net/ppp/pptp.c:358:26: warning: incorrect type in argument 1 (different base types)
> drivers/net/ppp/pptp.c:358:26:    expected unsigned short [usertype] call_id
> drivers/net/ppp/pptp.c:358:26:    got restricted __be16 [usertype]

Here we use the wrong flavour of byte-swap. Use ntohs(), which of course
gives the same result.

Cc: Dmitry Kozlov <xeb@...l.ru>
Signed-off-by: Julian Wiedmann <jwi@...ux.ibm.com>
---
 drivers/net/ppp/pptp.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index ee5058445d06..0fe78826c8fa 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -278,10 +278,8 @@ static int pptp_rcv_core(struct sock *sk, struct sk_buff *skb)
 		header = (struct pptp_gre_header *)(skb->data);
 
 		/* ack in different place if S = 0 */
-		ack = GRE_IS_SEQ(header->gre_hd.flags) ? header->ack : header->seq;
-
-		ack = ntohl(ack);
-
+		ack = GRE_IS_SEQ(header->gre_hd.flags) ? ntohl(header->ack) :
+							 ntohl(header->seq);
 		if (ack > opt->ack_recv)
 			opt->ack_recv = ack;
 		/* also handle sequence number wrap-around  */
@@ -355,7 +353,7 @@ static int pptp_rcv(struct sk_buff *skb)
 		/* if invalid, discard this packet */
 		goto drop;
 
-	po = lookup_chan(htons(header->call_id), iph->saddr);
+	po = lookup_chan(ntohs(header->call_id), iph->saddr);
 	if (po) {
 		skb_dst_drop(skb);
 		nf_reset_ct(skb);
-- 
2.17.1