diff options
| author | Wolfgang Bumiller <w.bumiller@proxmox.com> | 2018-04-12 10:46:55 +0200 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2019-05-03 18:57:35 +0200 |
| commit | d59aae2b1faf4150f25a272af3c186b78bf5a24d (patch) | |
| tree | 1901f941a96e85d24fba796eac3257ffdacb2452 | |
| parent | 0840edf56b874e11d7e39e6026414a6cf72a42e9 (diff) | |
net: fix deadlock while clearing neighbor proxy table
commit 53b76cdf7e8fecec1d09e38aad2f8579882591a8 upstream.
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.
Change-Id: I3e0bb9f41948210b1419fa35b3537d2a14afdd18
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>
[bwh: Backported to 3.16:
- Move the (useless) call to release_net() as well
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | net/core/neighbour.c | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 69e9b1703..cff5bec13 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -52,7 +52,8 @@ do { \ static void neigh_timer_handler(unsigned long arg); static void __neigh_notify(struct neighbour *n, int type, int flags); static void neigh_update_notify(struct neighbour *neigh); -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); static struct neigh_table *neigh_tables; #ifdef CONFIG_PROC_FS @@ -258,8 +259,7 @@ 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); @@ -657,9 +657,10 @@ 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++) { @@ -667,17 +668,24 @@ 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); - release_net(pneigh_net(n)); - 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); + release_net(pneigh_net(n)); + kfree(n); + } return -ENOENT; } |