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authorEric Dumazet <eric.dumazet@gmail.com>2011-08-08 20:56:14 +0000
committerDavid S. Miller <davem@davemloft.net>2011-08-09 21:47:14 -0700
commit9de79c127cccecb11ae6a21ab1499e87aa222880 (patch)
tree98173bcb0f620d078edc85f577b778b1f840ec3e /net/core/dst.c
parentMerge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net (diff)
downloadlinux-dev-9de79c127cccecb11ae6a21ab1499e87aa222880.tar.xz
linux-dev-9de79c127cccecb11ae6a21ab1499e87aa222880.zip
net: fix potential neighbour race in dst_ifdown()
Followup of commit f2c31e32b378a (fix NULL dereferences in check_peer_redir()). We need to make sure dst neighbour doesnt change in dst_ifdown(). Fix some sparse errors. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--net/core/dst.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
index 14b33baf0733..d5e2c4c09107 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -171,7 +171,7 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
dst_init_metrics(dst, dst_default_metrics, true);
dst->expires = 0UL;
dst->path = dst;
- dst->_neighbour = NULL;
+ RCU_INIT_POINTER(dst->_neighbour, NULL);
#ifdef CONFIG_XFRM
dst->xfrm = NULL;
#endif
@@ -229,11 +229,11 @@ struct dst_entry *dst_destroy(struct dst_entry * dst)
smp_rmb();
again:
- neigh = dst->_neighbour;
+ neigh = rcu_dereference_protected(dst->_neighbour, 1);
child = dst->child;
if (neigh) {
- dst->_neighbour = NULL;
+ RCU_INIT_POINTER(dst->_neighbour, NULL);
neigh_release(neigh);
}
@@ -360,14 +360,19 @@ static void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
if (!unregister) {
dst->input = dst->output = dst_discard;
} else {
+ struct neighbour *neigh;
+
dst->dev = dev_net(dst->dev)->loopback_dev;
dev_hold(dst->dev);
dev_put(dev);
- if (dst->_neighbour && dst->_neighbour->dev == dev) {
- dst->_neighbour->dev = dst->dev;
+ rcu_read_lock();
+ neigh = dst_get_neighbour(dst);
+ if (neigh && neigh->dev == dev) {
+ neigh->dev = dst->dev;
dev_hold(dst->dev);
dev_put(dev);
}
+ rcu_read_unlock();
}
}