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| author | Craig Gallek <kraig@google.com> | 2017-10-19 15:00:29 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-22 02:03:51 +0100 |
| commit | 1b5f962e71bfad6284574655c406597535c3ea7a (patch) | |
| tree | 2f96c8a5f8251654c8aaf3874681cd04c02b24e8 | |
| parent | 66c54517540cedf5a22911c6b7f5c7d8b5d1e1be (diff) | |
| download | linux-rpi-1b5f962e71bfad6284574655c406597535c3ea7a.tar.gz linux-rpi-1b5f962e71bfad6284574655c406597535c3ea7a.tar.bz2 linux-rpi-1b5f962e71bfad6284574655c406597535c3ea7a.zip | |
soreuseport: fix initialization race
Syzkaller stumbled upon a way to trigger
WARNING: CPU: 1 PID: 13881 at net/core/sock_reuseport.c:41
reuseport_alloc+0x306/0x3b0 net/core/sock_reuseport.c:39
There are two initialization paths for the sock_reuseport structure in a
socket: Through the udp/tcp bind paths of SO_REUSEPORT sockets or through
SO_ATTACH_REUSEPORT_[CE]BPF before bind. The existing implementation
assumedthat the socket lock protected both of these paths when it actually
only protects the SO_ATTACH_REUSEPORT path. Syzkaller triggered this
double allocation by running these paths concurrently.
This patch moves the check for double allocation into the reuseport_alloc
function which is protected by a global spin lock.
Fixes: e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection")
Fixes: c125e80b8868 ("soreuseport: fast reuseport TCP socket selection")
Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/sock_reuseport.c | 12 | ||||
| -rw-r--r-- | net/ipv4/inet_hashtables.c | 5 | ||||
| -rw-r--r-- | net/ipv4/udp.c | 5 |
3 files changed, 11 insertions, 11 deletions
diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c index eed1ebf7f29d..b1e0dbea1e8c 100644 --- a/net/core/sock_reuseport.c +++ b/net/core/sock_reuseport.c @@ -36,9 +36,14 @@ int reuseport_alloc(struct sock *sk) * soft irq of receive path or setsockopt from process context */ spin_lock_bh(&reuseport_lock); - WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb, - lockdep_is_held(&reuseport_lock)), - "multiple allocations for the same socket"); + + /* Allocation attempts can occur concurrently via the setsockopt path + * and the bind/hash path. Nothing to do when we lose the race. + */ + if (rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock))) + goto out; + reuse = __reuseport_alloc(INIT_SOCKS); if (!reuse) { spin_unlock_bh(&reuseport_lock); @@ -49,6 +54,7 @@ int reuseport_alloc(struct sock *sk) reuse->num_socks = 1; rcu_assign_pointer(sk->sk_reuseport_cb, reuse); +out: spin_unlock_bh(&reuseport_lock); return 0; diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 597bb4cfe805..e7d15fb0d94d 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -456,10 +456,7 @@ static int inet_reuseport_add_sock(struct sock *sk, return reuseport_add_sock(sk, sk2); } - /* Initial allocation may have already happened via setsockopt */ - if (!rcu_access_pointer(sk->sk_reuseport_cb)) - return reuseport_alloc(sk); - return 0; + return reuseport_alloc(sk); } int __inet_hash(struct sock *sk, struct sock *osk) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 806b298a3bdd..ebfbccae62fd 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -231,10 +231,7 @@ static int udp_reuseport_add_sock(struct sock *sk, struct udp_hslot *hslot) } } - /* Initial allocation may have already happened via setsockopt */ - if (!rcu_access_pointer(sk->sk_reuseport_cb)) - return reuseport_alloc(sk); - return 0; + return reuseport_alloc(sk); } /** |