linux-kernel - [PATCH net v5 09/10] ip6mr: Lock RCU before ip6mr_get_table() call in ip6mr_rtm

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Message-ID: <20241014151247.1902637-10-stefan.wiehler@nokia.com>
Date: Mon, 14 Oct 2024 17:05:55 +0200
From: Stefan Wiehler <stefan.wiehler@...ia.com>
To: "David S . Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Stefan Wiehler <stefan.wiehler@...ia.com>
Subject: [PATCH net v5 09/10] ip6mr: Lock RCU before ip6mr_get_table() call in ip6mr_rtm_getroute()

When IPV6_MROUTE_MULTIPLE_TABLES is enabled, calls to ip6mr_get_table()
must be done under RCU or RTNL lock.

Fixes: d1db275dd3f6 ("ipv6: ip6mr: support multiple tables")
Signed-off-by: Stefan Wiehler <stefan.wiehler@...ia.com>
---
 net/ipv6/ip6mr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index af921e9731ec..01b58156e06a 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -2594,14 +2594,15 @@ static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 		grp = nla_get_in6_addr(tb[RTA_DST]);
 	tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
 
+	rcu_read_lock();
 	mrt = ip6mr_get_table(net, tableid ?: RT_TABLE_DEFAULT);
 	if (!mrt) {
+		rcu_read_unlock();
 		NL_SET_ERR_MSG_MOD(extack, "MR table does not exist");
 		return -ENOENT;
 	}
 
 	/* entries are added/deleted only under RTNL */
-	rcu_read_lock();
 	cache = ip6mr_cache_find(mrt, &src, &grp);
 	rcu_read_unlock();
 	if (!cache) {
-- 
2.42.0