netdev - [PATCH iproute2-next 06/11] nexthop: fix clang warning about timer check

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Date:   Sat,  8 Jan 2022 12:46:45 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     netdev@...r.kernel.org
Cc:     Stephen Hemminger <sthemmin@...rosoft.com>, idosch@...dia.com
Subject: [PATCH iproute2-next 06/11] nexthop: fix clang warning about timer check

Clang correctly flags that ipnexthop is comparing timer
with a value that it can never have.

On 64 bit platform ~0UL / 100  = 184467440737095516
and timer is u32 so max is 4294967295.

Fixes: 91676718228b ("nexthop: Add support for resilient nexthop groups")
Cc: idosch@...dia.com
Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
 ip/ipnexthop.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/ip/ipnexthop.c b/ip/ipnexthop.c
index 83a5540e771c..2c65df294587 100644
--- a/ip/ipnexthop.c
+++ b/ip/ipnexthop.c
@@ -31,6 +31,8 @@ enum {
 	IPNH_FLUSH,
 };
 
+#define TIMER_MAX   (~(__u32)0 / 100)
+
 #define RTM_NHA(h)  ((struct rtattr *)(((char *)(h)) + \
 			NLMSG_ALIGN(sizeof(struct nhmsg))))
 
@@ -839,8 +841,8 @@ static void parse_nh_group_type_res(struct nlmsghdr *n, int maxlen, int *argcp,
 			__u32 idle_timer;
 
 			NEXT_ARG();
-			if (get_unsigned(&idle_timer, *argv, 0) ||
-			    idle_timer >= ~0UL / 100)
+			if (get_u32(&idle_timer, *argv, 0) ||
+			    idle_timer >= TIMER_MAX)
 				invarg("invalid idle timer value", *argv);
 
 			addattr32(n, maxlen, NHA_RES_GROUP_IDLE_TIMER,
@@ -849,8 +851,8 @@ static void parse_nh_group_type_res(struct nlmsghdr *n, int maxlen, int *argcp,
 			__u32 unbalanced_timer;
 
 			NEXT_ARG();
-			if (get_unsigned(&unbalanced_timer, *argv, 0) ||
-			    unbalanced_timer >= ~0UL / 100)
+			if (get_u32(&unbalanced_timer, *argv, 0) ||
+			    unbalanced_timer >= TIMER_MAX)
 				invarg("invalid unbalanced timer value", *argv);
 
 			addattr32(n, maxlen, NHA_RES_GROUP_UNBALANCED_TIMER,
-- 
2.30.2