From: Jakub Sitnicki jakub@cloudflare.com

[ Upstream commit 5b4a79ba65a1ab479903fff2e604865d229b70a9 ]

sock_map proto callbacks should never call themselves by design. Protect against bugs like [1] and break out of the recursive loop to avoid a stack overflow in favor of a resource leak.

[1] https://lore.kernel.org/all/00000000000073b14905ef2e7401@google.com/

Suggested-by: Eric Dumazet edumazet@google.com Signed-off-by: Jakub Sitnicki jakub@cloudflare.com Acked-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/r/20230113-sockmap-fix-v2-1-1e0ee7ac2f90@cloudflare.... Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org [Harinadh: Modified to apply on v5.10.y ] Signed-off-by: Harinadh Dommaraju Harinadh.Dommaraju@broadcom.com --- net/core/sock_map.c | 53 +++++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 3a9e0046a780..438bbef5ff75 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -1558,15 +1558,16 @@ void sock_map_unhash(struct sock *sk) psock = sk_psock(sk); if (unlikely(!psock)) { rcu_read_unlock(); - if (sk->sk_prot->unhash) - sk->sk_prot->unhash(sk); - return; + saved_unhash = READ_ONCE(sk->sk_prot)->unhash; + } else { + saved_unhash = psock->saved_unhash; + sock_map_remove_links(sk, psock); + rcu_read_unlock(); } - - saved_unhash = psock->saved_unhash; - sock_map_remove_links(sk, psock); - rcu_read_unlock(); - saved_unhash(sk); + if (WARN_ON_ONCE(saved_unhash == sock_map_unhash)) + return; + if (saved_unhash) + saved_unhash(sk); }

void sock_map_destroy(struct sock *sk) @@ -1578,16 +1579,17 @@ void sock_map_destroy(struct sock *sk) psock = sk_psock_get(sk); if (unlikely(!psock)) { rcu_read_unlock(); - if (sk->sk_prot->destroy) - sk->sk_prot->destroy(sk); - return; + saved_destroy = READ_ONCE(sk->sk_prot)->destroy; + } else { + saved_destroy = psock->saved_destroy; + sock_map_remove_links(sk, psock); + rcu_read_unlock(); + sk_psock_put(sk, psock); } - - saved_destroy = psock->saved_destroy; - sock_map_remove_links(sk, psock); - rcu_read_unlock(); - sk_psock_put(sk, psock); - saved_destroy(sk); + if (WARN_ON_ONCE(saved_destroy == sock_map_destroy)) + return; + if (saved_destroy) + saved_destroy(sk); } EXPORT_SYMBOL_GPL(sock_map_destroy);

@@ -1602,13 +1604,18 @@ void sock_map_close(struct sock *sk, long timeout) if (unlikely(!psock)) { rcu_read_unlock(); release_sock(sk); - return sk->sk_prot->close(sk, timeout); + saved_close = READ_ONCE(sk->sk_prot)->close; + } else { + saved_close = psock->saved_close; + sock_map_remove_links(sk, psock); + rcu_read_unlock(); + release_sock(sk); } - - saved_close = psock->saved_close; - sock_map_remove_links(sk, psock); - rcu_read_unlock(); - release_sock(sk); + /* Make sure we do not recurse. This is a bug. + * Leak the socket instead of crashing on a stack overflow. + */ + if (WARN_ON_ONCE(saved_close == sock_map_close)) + return; saved_close(sk, timeout); }