diff options
author | Stefano Garzarella <sgarzare@redhat.com> | 2020-02-26 11:58:18 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2020-02-27 21:03:56 +0100 |
commit | 3f74957fcbeab703297ed0f135430414ed7e0dd0 (patch) | |
tree | 1b8cadd1963b397e027e022e1ce2f04f7b378d6d /net/vmw_vsock/af_vsock.c | |
parent | unix: It's CONFIG_PROC_FS not CONFIG_PROCFS (diff) | |
download | linux-3f74957fcbeab703297ed0f135430414ed7e0dd0.tar.xz linux-3f74957fcbeab703297ed0f135430414ed7e0dd0.zip |
vsock: fix potential deadlock in transport->release()
Some transports (hyperv, virtio) acquire the sock lock during the
.release() callback.
In the vsock_stream_connect() we call vsock_assign_transport(); if
the socket was previously assigned to another transport, the
vsk->transport->release() is called, but the sock lock is already
held in the vsock_stream_connect(), causing a deadlock reported by
syzbot:
INFO: task syz-executor280:9768 blocked for more than 143 seconds.
Not tainted 5.6.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor280 D27912 9768 9766 0x00000000
Call Trace:
context_switch kernel/sched/core.c:3386 [inline]
__schedule+0x934/0x1f90 kernel/sched/core.c:4082
schedule+0xdc/0x2b0 kernel/sched/core.c:4156
__lock_sock+0x165/0x290 net/core/sock.c:2413
lock_sock_nested+0xfe/0x120 net/core/sock.c:2938
virtio_transport_release+0xc4/0xd60 net/vmw_vsock/virtio_transport_common.c:832
vsock_assign_transport+0xf3/0x3b0 net/vmw_vsock/af_vsock.c:454
vsock_stream_connect+0x2b3/0xc70 net/vmw_vsock/af_vsock.c:1288
__sys_connect_file+0x161/0x1c0 net/socket.c:1857
__sys_connect+0x174/0x1b0 net/socket.c:1874
__do_sys_connect net/socket.c:1885 [inline]
__se_sys_connect net/socket.c:1882 [inline]
__x64_sys_connect+0x73/0xb0 net/socket.c:1882
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
To avoid this issue, this patch remove the lock acquiring in the
.release() callback of hyperv and virtio transports, and it holds
the lock when we call vsk->transport->release() in the vsock core.
Reported-by: syzbot+731710996d79d0d58fbc@syzkaller.appspotmail.com
Fixes: 408624af4c89 ("vsock: use local transport when it is loaded")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/vmw_vsock/af_vsock.c')
-rw-r--r-- | net/vmw_vsock/af_vsock.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 9c5b2a91baad..a5f28708e0e7 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -451,6 +451,12 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) if (vsk->transport == new_transport) return 0; + /* transport->release() must be called with sock lock acquired. + * This path can only be taken during vsock_stream_connect(), + * where we have already held the sock lock. + * In the other cases, this function is called on a new socket + * which is not assigned to any transport. + */ vsk->transport->release(vsk); vsock_deassign_transport(vsk); } @@ -753,20 +759,18 @@ static void __vsock_release(struct sock *sk, int level) vsk = vsock_sk(sk); pending = NULL; /* Compiler warning. */ - /* The release call is supposed to use lock_sock_nested() - * rather than lock_sock(), if a sock lock should be acquired. - */ - if (vsk->transport) - vsk->transport->release(vsk); - else if (sk->sk_type == SOCK_STREAM) - vsock_remove_sock(vsk); - /* When "level" is SINGLE_DEPTH_NESTING, use the nested * version to avoid the warning "possible recursive locking * detected". When "level" is 0, lock_sock_nested(sk, level) * is the same as lock_sock(sk). */ lock_sock_nested(sk, level); + + if (vsk->transport) + vsk->transport->release(vsk); + else if (sk->sk_type == SOCK_STREAM) + vsock_remove_sock(vsk); + sock_orphan(sk); sk->sk_shutdown = SHUTDOWN_MASK; |