[PATCH net] tipc: fix division by zero in perc()

[Tristan Madani <tristmd@gmail.com>]

From: Tristan Madani <tristan@talencesecurity.com>

The perc() function divides count by total without checking whether
total is zero. When link statistics are queried on a freshly
established link that has not yet exchanged messages,
TIPC_NLA_STATS_MSG_PROF_TOT is zero, causing a division by zero
in tipc_nl_compat_link_stat_dump().

Add a zero check to return 0 when total is zero.

Fixes: f2b3b2d4ccbf ("tipc: convert legacy nl link stat to nl compat")
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 net/tipc/netlink_compat.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index d9a4f94ea2d43..75f3193a2a6cf 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -497,6 +497,9 @@ static int tipc_nl_compat_bearer_disable(struct tipc_nl_compat_cmd_doit *cmd,
 
 static inline u32 perc(u32 count, u32 total)
 {
+	if (!total)
+		return 0;
+
 	return (count * 100 + (total / 2)) / total;
 }
 
-- 
2.47.3