linux-kernel - [PATCH v2 net] ipvs: Fix clamp() order in ip_vs_conn

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Message-ID: <Z1m2RVCy-lkXdDUa@stanley.mountain>
Date: Wed, 11 Dec 2024 18:56:53 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Julian Anastasov <ja@....bg>
Cc: Simon Horman <horms@...ge.net.au>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Jozsef Kadlecsik <kadlec@...filter.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, lvs-devel@...r.kernel.org,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	linux-kernel@...r.kernel.org, Bartosz Golaszewski <brgl@...ev.pl>,
	David Laight <David.Laight@...lab.com>
Subject: [PATCH v2 net] ipvs: Fix clamp() order in ip_vs_conn_init()

We recently added some build time asserts to detect incorrect calls to
clamp and it detected this bug which breaks the build.  The variable
in this clamp is "max_avail" and it should be the first argument.  The
code currently is the equivalent to max = min(max_avail, max).

There probably aren't very many systems out there where we actually can
hit the minimum value so this doesn't affect runtime for most people.

Reported-by: Linux Kernel Functional Testing <lkft@...aro.org>
Closes: https://lore.kernel.org/all/CA+G9fYsT34UkGFKxus63H6UVpYi5GRZkezT9MRLfAbM3f6ke0g@mail.gmail.com/
Suggested-by: David Laight <David.Laight@...LAB.COM>
Fixes: 4f325e26277b ("ipvs: dynamically limit the connection hash table")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
Tested-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
v2: In the commit message, I said max() but it should have been min().
    I added a note that this bug probably doesn't affect too many
    people in real life.  I also added David Laight as a Suggested-by
    because he did all the work root causing this bug and he already
    sent a similar patch last week.

    Added Bartosz's tested by tags.

 net/netfilter/ipvs/ip_vs_conn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 98d7dbe3d787..9f75ac801301 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -1495,7 +1495,7 @@ int __init ip_vs_conn_init(void)
 	max_avail -= 2;		/* ~4 in hash row */
 	max_avail -= 1;		/* IPVS up to 1/2 of mem */
 	max_avail -= order_base_2(sizeof(struct ip_vs_conn));
-	max = clamp(max, min, max_avail);
+	max = clamp(max_avail, min, max);
 	ip_vs_conn_tab_bits = clamp_val(ip_vs_conn_tab_bits, min, max);
 	ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
 	ip_vs_conn_tab_mask = ip_vs_conn_tab_size - 1;
-- 
2.45.2