netdev - [PATCH net-next] net: fib_notifier: don't return positive values on fib registration

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Date:   Thu, 11 Feb 2021 12:07:59 +0200
From:   Vlad Buslov <vladbu@...dia.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>
CC:     <netdev@...r.kernel.org>, Vlad Buslov <vladbu@...dia.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Ido Schimmel <idosch@...dia.com>
Subject: [PATCH net-next] net: fib_notifier: don't return positive values on fib registration

The function fib6_walk_continue() cannot return a positive value when
called from register_fib_notifier(), but ignoring causes static analyzer to
generate warnings in users of register_fib_notifier() that try to convert
returned error code to pointer with ERR_PTR(). Handle such case by
explicitly checking for positive error values and converting them to
-EINVAL in fib6_tables_dump().

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Suggested-by: Ido Schimmel <idosch@...dia.com>
Signed-off-by: Vlad Buslov <vladbu@...dia.com>
---
 net/ipv6/ip6_fib.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index f43e27555725..ef9d022e693f 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -499,7 +499,7 @@ int fib6_tables_dump(struct net *net, struct notifier_block *nb,
 
 		hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 			err = fib6_table_dump(net, tb, w);
-			if (err < 0)
+			if (err)
 				goto out;
 		}
 	}
@@ -507,7 +507,8 @@ int fib6_tables_dump(struct net *net, struct notifier_block *nb,
 out:
 	kfree(w);
 
-	return err;
+	/* The tree traversal function should never return a positive value. */
+	return err > 0 ? -EINVAL : err;
 }
 
 static int fib6_dump_node(struct fib6_walker *w)
-- 
2.29.2