netdev - [PATCH iproute2] ip/ipnexthop: fix unsigned overflow in parse_nh_group_type

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Message-ID: <91362fa6-46df-c134-63b1-cc2b0d2832ee@gmail.com>
Date:   Wed, 17 Nov 2021 22:11:24 +0300
From:   Maxim Petrov <mmrmaximuzz@...il.com>
To:     netdev@...r.kernel.org
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        David Miller <davem@...emloft.net>, mmrmaximuzz@...il.com
Subject: [PATCH iproute2] ip/ipnexthop: fix unsigned overflow in
 parse_nh_group_type_res()

0UL has type 'unsigned long' which is likely to be 64bit on modern machines. At
the same time, the '{idle,unbalanced}_timer' variables are declared as u32, so
these variables cannot be greater than '~0UL / 100' when 'unsigned long' is 64
bits. In such condition it is still possible to pass the check but get the
overflow later when the timers are multiplied by 100 in 'addattr32'.

Fix the possible overflow by changing '~0UL' to 'UINT32_MAX'.

Signed-off-by: Maxim Petrov <mmrmaximuzz@...il.com>
---
 ip/ipnexthop.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/ip/ipnexthop.c b/ip/ipnexthop.c
index 83a5540e..2f448449 100644
--- a/ip/ipnexthop.c
+++ b/ip/ipnexthop.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/nexthop.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <string.h>
 #include <rt_names.h>
@@ -840,7 +841,7 @@ static void parse_nh_group_type_res(struct nlmsghdr *n, int maxlen, int *argcp,
 
 			NEXT_ARG();
 			if (get_unsigned(&idle_timer, *argv, 0) ||
-			    idle_timer >= ~0UL / 100)
+			    idle_timer >= UINT32_MAX / 100)
 				invarg("invalid idle timer value", *argv);
 
 			addattr32(n, maxlen, NHA_RES_GROUP_IDLE_TIMER,
@@ -850,7 +851,7 @@ static void parse_nh_group_type_res(struct nlmsghdr *n, int maxlen, int *argcp,
 
 			NEXT_ARG();
 			if (get_unsigned(&unbalanced_timer, *argv, 0) ||
-			    unbalanced_timer >= ~0UL / 100)
+			    unbalanced_timer >= UINT32_MAX / 100)
 				invarg("invalid unbalanced timer value", *argv);
 
 			addattr32(n, maxlen, NHA_RES_GROUP_UNBALANCED_TIMER,
-- 
2.25.1