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: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets") Signed-off-by: Eric Dumazet <eduma...@google.com> Cc: Johannes Weiner <han...@cmpxchg.org> Cc: Tejun Heo <t...@kernel.org> --- kernel/cgroup/cgroup.c | 11 ----------- net/core/sock.c | 3 +-- net/ipv4/inet_connection_sock.c | 5 +++++ 3 files changed, 6 insertions(+), 13 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 44857278eb8aa6a2bbf27b7eb12137ef42628170..3380a3e49af501e457991b2823020494cf32af80 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5709,17 +5709,6 @@ void cgroup_sk_alloc(struct sock_cgroup_data *skcd) if (cgroup_sk_alloc_disabled) return; - /* Socket clone path */ - if (skcd->val) { - /* - * We might be cloning a socket which is left in an empty - * cgroup and the cgroup might have already been rmdir'd. - * Don't use cgroup_get_live(). - */ - cgroup_get(sock_cgroup_ptr(skcd)); - return; - } - rcu_read_lock(); while (true) { diff --git a/net/core/sock.c b/net/core/sock.c index 70c6ccbdf49f2f8a5a0f7c41c7849ea01459be50..4499e31538132ed59a16d92e6f6b923e776df84e 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -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) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 67aec7a106860b26c929fea1624d652c87972f04..d32c74507314cc4b91d040de8e877e4bd8204106 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -26,6 +26,8 @@ #include <net/tcp.h> #include <net/sock_reuseport.h> #include <net/addrconf.h> +#include <net/cls_cgroup.h> +#include <net/netprio_cgroup.h> #ifdef INET_CSK_DEBUG const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n"; @@ -476,6 +478,9 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) spin_unlock_bh(&queue->fastopenq.lock); } mem_cgroup_sk_alloc(newsk); + cgroup_sk_alloc(&newsk->sk_cgrp_data); + sock_update_classid(&newsk->sk_cgrp_data); + sock_update_netprioidx(&newsk->sk_cgrp_data); out: release_sock(sk); if (req) -- 2.14.2.920.gcf0c67979c-goog