diff options
| 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 /net/core | |
| parent | 66c54517540cedf5a22911c6b7f5c7d8b5d1e1be (diff) | |
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>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/sock_reuseport.c | 12 |
1 files changed, 9 insertions, 3 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; |