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| author | Florian Westphal <fw@strlen.de> | 2015-10-08 23:38:07 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2015-10-13 13:59:56 +0200 |
| commit | 514ed62ed3f6846325d9bfb15cb5c3540547f13b (patch) | |
| tree | 3293f233a9b21034a0f98d6a9043844b15efe718 | |
| parent | cc4998febd567d1c671684abce5595344bd4e8b2 (diff) | |
| download | linux-514ed62ed3f6846325d9bfb15cb5c3540547f13b.tar.gz linux-514ed62ed3f6846325d9bfb15cb5c3540547f13b.tar.xz | |
netfilter: sync with packet rx also after removing queue entries
We need to sync packet rx again after flushing the queue entries.
Otherwise, the following race could happen:
cpu1: nf_unregister_hook(H) called, H unliked from lists, calls
synchronize_net() to wait for packet rx completion.
Problem is that while no new nf_queue_entry structs that use H can be
allocated, another CPU might receive a verdict from userspace just before
cpu1 calls nf_queue_nf_hook_drop to remove this entry:
cpu2: receive verdict from userspace, lock queue
cpu2: unlink nf_queue_entry struct E, which references H, from queue list
cpu1: calls nf_queue_nf_hook_drop, blocks on queue spinlock
cpu2: unlock queue
cpu1: nf_queue_nf_hook_drop drops affected queue entries
cpu2: call nf_reinject for E
cpu1: kfree(H)
cpu2: potential use-after-free for H
Cc: Eric W. Biederman <ebiederm@xmission.com>
Fixes: 085db2c04557 ("netfilter: Per network namespace netfilter hooks.")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/core.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 8e47f8113495..21a085686dc1 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -152,6 +152,8 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg) #endif synchronize_net(); nf_queue_nf_hook_drop(net, &entry->ops); + /* other cpu might still process nfqueue verdict that used reg */ + synchronize_net(); kfree(entry); } EXPORT_SYMBOL(nf_unregister_net_hook); |