netdev - [PATCH net-next 1/2] net: sched: act

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Message-Id: <20190617100327.24796-2-ldir@darbyshire-bryant.me.uk>
Date:   Mon, 17 Jun 2019 11:03:26 +0100
From:   Kevin Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
To:     netdev@...r.kernel.org
Cc:     Kevin Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
Subject: [PATCH net-next 1/2] net: sched: act_ctinfo: fix action creation

Use correct return value on action creation: ACT_P_CREATED.

The use of incorrect return value could result in a situation where the
system thought a ctinfo module was listening but actually wasn't
instantiated correctly leading to an OOPS in tcf_generic_walker().

Confession time: Until very recently, development of this module has
been done on 'net-next' tree to 'clean compile' level with run-time
testing on backports to 4.14 & 4.19 kernels under openwrt.  During the
back & forward porting during development & testing, the critical
ACT_P_CREATED return code got missed despite being in the 4.14 & 4.19
backports.  I have now gone through the init functions, using act_csum
as reference with a fine toothed comb.  Bonus, no more OOPSes.  I
managed to also miss this issue till now due to the new strict
nla_parse_nested function failing validation before action creation.

As an inexperienced developer I've learned that
copy/pasting/backporting/forward porting code correctly is hard.  If I
ever get to a developer conference I shall don the cone of shame.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
---
 net/sched/act_ctinfo.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/act_ctinfo.c b/net/sched/act_ctinfo.c
index a7d3679d7e2e..2c17f6843107 100644
--- a/net/sched/act_ctinfo.c
+++ b/net/sched/act_ctinfo.c
@@ -213,6 +213,7 @@ static int tcf_ctinfo_init(struct net *net, struct nlattr *nla,
 			tcf_idr_cleanup(tn, actparm->index);
 			return ret;
 		}
+		ret = ACT_P_CREATED;
 	} else if (err > 0) {
 		if (bind) /* don't override defaults */
 			return 0;
-- 
2.20.1 (Apple Git-117)