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

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

[Tristan Madani]

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

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

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

Please do not repost the series just to address the above. Instead,
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