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authorWolfgang Bumiller2018-04-12 10:46:55 +0200
committerDavid S. Miller2018-04-12 22:01:22 -0400
commit53b76cdf7e8fecec1d09e38aad2f8579882591a8 (patch)
tree1c6912ae100a38fd342e72324cd2d93edc38b161
parent1071ec9d453a38023579714b64a951a2fb982071 (diff)
net: fix deadlock while clearing neighbor proxy table
When coming from ndisc_netdev_event() in net/ipv6/ndisc.c, neigh_ifdown() is called with &nd_tbl, locking this while clearing the proxy neighbor entries when eg. deleting an interface. Calling the table's pndisc_destructor() with the lock still held, however, can cause a deadlock: When a multicast listener is available an IGMP packet of type ICMPV6_MGM_REDUCTION may be sent out. When reaching ip6_finish_output2(), if no neighbor entry for the target address is found, __neigh_create() is called with &nd_tbl, which it'll want to lock. Move the elements into their own list, then unlock the table and perform the destruction. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199289 Fixes: 6fd6ce2056de ("ipv6: Do not depend on rt->n in ip6_finish_output2().") Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/neighbour.c28
1 files changed, 18 insertions, 10 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index a8bc02bb339f..ce519861be59 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -55,7 +55,8 @@ static void neigh_timer_handler(struct timer_list *t);
static void __neigh_notify(struct neighbour *n, int type, int flags,
u32 pid);
static void neigh_update_notify(struct neighbour *neigh, u32 nlmsg_pid);
-static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
+static int pneigh_ifdown_and_unlock(struct neigh_table *tbl,
+ struct net_device *dev);
#ifdef CONFIG_PROC_FS
static const struct file_operations neigh_stat_seq_fops;
@@ -291,8 +292,7 @@ int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
{
write_lock_bh(&tbl->lock);
neigh_flush_dev(tbl, dev);
- pneigh_ifdown(tbl, dev);
- write_unlock_bh(&tbl->lock);
+ pneigh_ifdown_and_unlock(tbl, dev);
del_timer_sync(&tbl->proxy_timer);
pneigh_queue_purge(&tbl->proxy_queue);
@@ -681,9 +681,10 @@ int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *pkey,
return -ENOENT;
}
-static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
+static int pneigh_ifdown_and_unlock(struct neigh_table *tbl,
+ struct net_device *dev)
{
- struct pneigh_entry *n, **np;
+ struct pneigh_entry *n, **np, *freelist = NULL;
u32 h;
for (h = 0; h <= PNEIGH_HASHMASK; h++) {
@@ -691,16 +692,23 @@ static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
while ((n = *np) != NULL) {
if (!dev || n->dev == dev) {
*np = n->next;
- if (tbl->pdestructor)
- tbl->pdestructor(n);
- if (n->dev)
- dev_put(n->dev);
- kfree(n);
+ n->next = freelist;
+ freelist = n;
continue;
}
np = &n->next;
}
}
+ write_unlock_bh(&tbl->lock);
+ while ((n = freelist)) {
+ freelist = n->next;
+ n->next = NULL;
+ if (tbl->pdestructor)
+ tbl->pdestructor(n);
+ if (n->dev)
+ dev_put(n->dev);
+ kfree(n);
+ }
return -ENOENT;
}