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net: defer call to cgroup_sk_alloc()

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sk_clone_lock() might run while TCP/DCCP listener already vanished.

In order to prevent use after free, it is better to defer cgroup_sk_alloc()
to the point we know both parent and child exist, and from process context.

Fixes: e994b2f0fb ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-10-08 21:44:52 -07:00 • committed by David S. Miller
parent 9f1c2674b3
commit fbb1fb4ad4
3 changed files with 6 additions and 13 deletions
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3
net/core/sock.c
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@ -1680,6 +1680,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
/* sk->sk_memcg will be populated at accept() time */
newsk->sk_memcg = NULL;
memset(&newsk->sk_cgrp_data, 0, sizeof(newsk->sk_cgrp_data));
atomic_set(&newsk->sk_drops, 0);
newsk->sk_send_head = NULL;
@ -1718,8 +1719,6 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
newsk->sk_incoming_cpu = raw_smp_processor_id();
atomic64_set(&newsk->sk_cookie, 0);
cgroup_sk_alloc(&newsk->sk_cgrp_data);
/*
* Before updating sk_refcnt, we must commit prior changes to memory
* (Documentation/RCU/rculist_nulls.txt for details)