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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2019-02-01 00:05:49 +0300 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2019-02-05 08:29:20 +0300 |
| commit | f75a2804da391571563c4b6b29e7797787332673 (patch) | |
| tree | ab0938d51019534539a0e2585cca20a82f8557af /net/key | |
| parent | 09db51241118aeb06e1c8cd393b45879ce099b36 (diff) | |
| download | linux-f75a2804da391571563c4b6b29e7797787332673.tar.xz | |
xfrm: destroy xfrm_state synchronously on net exit path
xfrm_state_put() moves struct xfrm_state to the GC list
and schedules the GC work to clean it up. On net exit call
path, xfrm_state_flush() is called to clean up and
xfrm_flush_gc() is called to wait for the GC work to complete
before exit.
However, this doesn't work because one of the ->destructor(),
ipcomp_destroy(), schedules the same GC work again inside
the GC work. It is hard to wait for such a nested async
callback. This is also why syzbot still reports the following
warning:
WARNING: CPU: 1 PID: 33 at net/ipv6/xfrm6_tunnel.c:351 xfrm6_tunnel_net_exit+0x2cb/0x500 net/ipv6/xfrm6_tunnel.c:351
...
ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:153
cleanup_net+0x51d/0xb10 net/core/net_namespace.c:551
process_one_work+0xd0c/0x1ce0 kernel/workqueue.c:2153
worker_thread+0x143/0x14a0 kernel/workqueue.c:2296
kthread+0x357/0x430 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
In fact, it is perfectly fine to bypass GC and destroy xfrm_state
synchronously on net exit call path, because it is in process context
and doesn't need a work struct to do any blocking work.
This patch introduces xfrm_state_put_sync() which simply bypasses
GC, and lets its callers to decide whether to use this synchronous
version. On net exit path, xfrm_state_fini() and
xfrm6_tunnel_net_exit() use it. And, as ipcomp_destroy() itself is
blocking, it can use xfrm_state_put_sync() directly too.
Also rename xfrm_state_gc_destroy() to ___xfrm_state_destroy() to
reflect this change.
Fixes: b48c05ab5d32 ("xfrm: Fix warning in xfrm6_tunnel_net_exit.")
Reported-and-tested-by: syzbot+e9aebef558e3ed673934@syzkaller.appspotmail.com
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/key')
| -rw-r--r-- | net/key/af_key.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/key/af_key.c b/net/key/af_key.c index 655c787f9d54..637030f43b67 100644 --- a/net/key/af_key.c +++ b/net/key/af_key.c @@ -1783,7 +1783,7 @@ static int pfkey_flush(struct sock *sk, struct sk_buff *skb, const struct sadb_m if (proto == 0) return -EINVAL; - err = xfrm_state_flush(net, proto, true); + err = xfrm_state_flush(net, proto, true, false); err2 = unicast_flush_resp(sk, hdr); if (err || err2) { if (err == -ESRCH) /* empty table - go quietly */ |