From 55b8050353c4a212c94d7156e2bd5885225b869b Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 19 Oct 2009 06:41:58 +0000
Subject: [PATCH] net: Fix IP_MULTICAST_IF
ipv4/ipv6 setsockopt(IP_MULTICAST_IF) have dubious __dev_get_by_index() calls.
This function should be called only with RTNL or dev_base_lock held, or reader
could see a corrupt hash chain and eventually enter an endless loop.
Fix is to call dev_get_by_index()/dev_put().
If this happens to be performance critical, we could define a new dev_exist_by_index()
function to avoid touching dev refcount.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/ip_sockglue.c | 7 +++----
net/ipv6/ipv6_sockglue.c | 6 +++++-
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 0c0b6e363a20..e982b5c1ee17 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -634,17 +634,16 @@ static int do_ip_setsockopt(struct sock *sk, int level,
break;
}
dev = ip_dev_find(sock_net(sk), mreq.imr_address.s_addr);
- if (dev) {
+ if (dev)
mreq.imr_ifindex = dev->ifindex;
- dev_put(dev);
- }
} else
- dev = __dev_get_by_index(sock_net(sk), mreq.imr_ifindex);
+ dev = dev_get_by_index(sock_net(sk), mreq.imr_ifindex);
err = -EADDRNOTAVAIL;
if (!dev)
break;
+ dev_put(dev);
err = -EINVAL;
if (sk->sk_bound_dev_if &&
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 14f54eb5a7fc..4f7aaf6996a3 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -496,13 +496,17 @@ done:
goto e_inval;
if (val) {
+ struct net_device *dev;
+
if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != val)
goto e_inval;
- if (__dev_get_by_index(net, val) == NULL) {
+ dev = dev_get_by_index(net, val);
+ if (!dev) {
retv = -ENODEV;
break;
}
+ dev_put(dev);
}
np->mcast_oif = val;
retv = 0;
--
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