From 2cb7c756f605ec02ffe562fb26828e4bcc5fdfc1 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Fri, 10 Jan 2025 09:35:07 +0100 Subject: [PATCH 1/5] vsock/virtio: discard packets if the transport changes If the socket has been de-assigned or assigned to another transport, we must discard any packets received because they are not expected and would cause issues when we access vsk->transport. A possible scenario is described by Hyunwoo Kim in the attached link, where after a first connect() interrupted by a signal, and a second connect() failed, we can find `vsk->transport` at NULL, leading to a NULL pointer dereference. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Cc: stable@vger.kernel.org Reported-by: Hyunwoo Kim Reported-by: Wongi Lee Closes: https://lore.kernel.org/netdev/Z2LvdTTQR7dBmPb5@v4bel-B760M-AORUS-ELITE-AX/ Signed-off-by: Stefano Garzarella Reviewed-by: Hyunwoo Kim Signed-off-by: Paolo Abeni --- net/vmw_vsock/virtio_transport_common.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 9acc13ab3f822..51a494b69be84 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -1628,8 +1628,11 @@ void virtio_transport_recv_pkt(struct virtio_transport *t, lock_sock(sk); - /* Check if sk has been closed before lock_sock */ - if (sock_flag(sk, SOCK_DONE)) { + /* Check if sk has been closed or assigned to another transport before + * lock_sock (note: listener sockets are not assigned to any transport) + */ + if (sock_flag(sk, SOCK_DONE) || + (sk->sk_state != TCP_LISTEN && vsk->transport != &t->transport)) { (void)virtio_transport_reset_no_sock(t, skb); release_sock(sk); sock_put(sk); From f6abafcd32f9cfc4b1a2f820ecea70773e26d423 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Fri, 10 Jan 2025 09:35:08 +0100 Subject: [PATCH 2/5] vsock/bpf: return early if transport is not assigned Some of the core functions can only be called if the transport has been assigned. As Michal reported, a socket might have the transport at NULL, for example after a failed connect(), causing the following trace: BUG: kernel NULL pointer dereference, address: 00000000000000a0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 12faf8067 P4D 12faf8067 PUD 113670067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 15 UID: 0 PID: 1198 Comm: a.out Not tainted 6.13.0-rc2+ RIP: 0010:vsock_connectible_has_data+0x1f/0x40 Call Trace: vsock_bpf_recvmsg+0xca/0x5e0 sock_recvmsg+0xb9/0xc0 __sys_recvfrom+0xb3/0x130 __x64_sys_recvfrom+0x20/0x30 do_syscall_64+0x93/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e So we need to check the `vsk->transport` in vsock_bpf_recvmsg(), especially for connected sockets (stream/seqpacket) as we already do in __vsock_connectible_recvmsg(). Fixes: 634f1a7110b4 ("vsock: support sockmap") Cc: stable@vger.kernel.org Reported-by: Michal Luczaj Closes: https://lore.kernel.org/netdev/5ca20d4c-1017-49c2-9516-f6f75fd331e9@rbox.co/ Tested-by: Michal Luczaj Reported-by: syzbot+3affdbfc986ecd9200fd@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/677f84a8.050a0220.25a300.01b3.GAE@google.com/ Tested-by: syzbot+3affdbfc986ecd9200fd@syzkaller.appspotmail.com Reviewed-by: Hyunwoo Kim Acked-by: Michael S. Tsirkin Reviewed-by: Luigi Leonardi Signed-off-by: Stefano Garzarella Signed-off-by: Paolo Abeni --- net/vmw_vsock/vsock_bpf.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/vmw_vsock/vsock_bpf.c b/net/vmw_vsock/vsock_bpf.c index 4aa6e74ec2957..f201d9eca1df2 100644 --- a/net/vmw_vsock/vsock_bpf.c +++ b/net/vmw_vsock/vsock_bpf.c @@ -77,6 +77,7 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags, int *addr_len) { struct sk_psock *psock; + struct vsock_sock *vsk; int copied; psock = sk_psock_get(sk); @@ -84,6 +85,13 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, return __vsock_recvmsg(sk, msg, len, flags); lock_sock(sk); + vsk = vsock_sk(sk); + + if (!vsk->transport) { + copied = -ENODEV; + goto out; + } + if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) { release_sock(sk); sk_psock_put(sk, psock); @@ -108,6 +116,7 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, copied = sk_msg_recvmsg(sk, psock, msg, len, flags); } +out: release_sock(sk); sk_psock_put(sk, psock); From df137da9d6d166e87e40980e36eb8e0bc90483ef Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Fri, 10 Jan 2025 09:35:09 +0100 Subject: [PATCH 3/5] vsock/virtio: cancel close work in the destructor During virtio_transport_release() we can schedule a delayed work to perform the closing of the socket before destruction. The destructor is called either when the socket is really destroyed (reference counter to zero), or it can also be called when we are de-assigning the transport. In the former case, we are sure the delayed work has completed, because it holds a reference until it completes, so the destructor will definitely be called after the delayed work is finished. But in the latter case, the destructor is called by AF_VSOCK core, just after the release(), so there may still be delayed work scheduled. Refactor the code, moving the code to delete the close work already in the do_close() to a new function. Invoke it during destruction to make sure we don't leave any pending work. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Cc: stable@vger.kernel.org Reported-by: Hyunwoo Kim Closes: https://lore.kernel.org/netdev/Z37Sh+utS+iV3+eb@v4bel-B760M-AORUS-ELITE-AX/ Signed-off-by: Stefano Garzarella Reviewed-by: Luigi Leonardi Tested-by: Hyunwoo Kim Signed-off-by: Paolo Abeni --- net/vmw_vsock/virtio_transport_common.c | 29 ++++++++++++++++++------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 51a494b69be84..7f7de6d880965 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -26,6 +26,9 @@ /* Threshold for detecting small packets to copy */ #define GOOD_COPY_LEN 128 +static void virtio_transport_cancel_close_work(struct vsock_sock *vsk, + bool cancel_timeout); + static const struct virtio_transport * virtio_transport_get_ops(struct vsock_sock *vsk) { @@ -1109,6 +1112,8 @@ void virtio_transport_destruct(struct vsock_sock *vsk) { struct virtio_vsock_sock *vvs = vsk->trans; + virtio_transport_cancel_close_work(vsk, true); + kfree(vvs); vsk->trans = NULL; } @@ -1204,17 +1209,11 @@ static void virtio_transport_wait_close(struct sock *sk, long timeout) } } -static void virtio_transport_do_close(struct vsock_sock *vsk, - bool cancel_timeout) +static void virtio_transport_cancel_close_work(struct vsock_sock *vsk, + bool cancel_timeout) { struct sock *sk = sk_vsock(vsk); - sock_set_flag(sk, SOCK_DONE); - vsk->peer_shutdown = SHUTDOWN_MASK; - if (vsock_stream_has_data(vsk) <= 0) - sk->sk_state = TCP_CLOSING; - sk->sk_state_change(sk); - if (vsk->close_work_scheduled && (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) { vsk->close_work_scheduled = false; @@ -1226,6 +1225,20 @@ static void virtio_transport_do_close(struct vsock_sock *vsk, } } +static void virtio_transport_do_close(struct vsock_sock *vsk, + bool cancel_timeout) +{ + struct sock *sk = sk_vsock(vsk); + + sock_set_flag(sk, SOCK_DONE); + vsk->peer_shutdown = SHUTDOWN_MASK; + if (vsock_stream_has_data(vsk) <= 0) + sk->sk_state = TCP_CLOSING; + sk->sk_state_change(sk); + + virtio_transport_cancel_close_work(vsk, cancel_timeout); +} + static void virtio_transport_close_timeout(struct work_struct *work) { struct vsock_sock *vsk = From a24009bc9be60242651a21702609381b5092459e Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Fri, 10 Jan 2025 09:35:10 +0100 Subject: [PATCH 4/5] vsock: reset socket state when de-assigning the transport Transport's release() and destruct() are called when de-assigning the vsock transport. These callbacks can touch some socket state like sock flags, sk_state, and peer_shutdown. Since we are reassigning the socket to a new transport during vsock_connect(), let's reset these fields to have a clean state with the new transport. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Reviewed-by: Luigi Leonardi Signed-off-by: Paolo Abeni --- net/vmw_vsock/af_vsock.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 5cf8109f672a5..74d35a8716446 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -491,6 +491,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) */ vsk->transport->release(vsk); vsock_deassign_transport(vsk); + + /* transport's release() and destruct() can touch some socket + * state, since we are reassigning the socket to a new transport + * during vsock_connect(), let's reset these fields to have a + * clean state. + */ + sock_reset_flag(sk, SOCK_DONE); + sk->sk_state = TCP_CLOSE; + vsk->peer_shutdown = 0; } /* We increase the module refcnt to prevent the transport unloading From 91751e248256efc111e52e15115840c35d85abaf Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Fri, 10 Jan 2025 09:35:11 +0100 Subject: [PATCH 5/5] vsock: prevent null-ptr-deref in vsock_*[has_data|has_space] Recent reports have shown how we sometimes call vsock_*_has_data() when a vsock socket has been de-assigned from a transport (see attached links), but we shouldn't. Previous commits should have solved the real problems, but we may have more in the future, so to avoid null-ptr-deref, we can return 0 (no space, no data available) but with a warning. This way the code should continue to run in a nearly consistent state and have a warning that allows us to debug future problems. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/netdev/Z2K%2FI4nlHdfMRTZC@v4bel-B760M-AORUS-ELITE-AX/ Link: https://lore.kernel.org/netdev/5ca20d4c-1017-49c2-9516-f6f75fd331e9@rbox.co/ Link: https://lore.kernel.org/netdev/677f84a8.050a0220.25a300.01b3.GAE@google.com/ Co-developed-by: Hyunwoo Kim Signed-off-by: Hyunwoo Kim Co-developed-by: Wongi Lee Signed-off-by: Wongi Lee Signed-off-by: Stefano Garzarella Reviewed-by: Luigi Leonardi Reviewed-by: Hyunwoo Kim Signed-off-by: Paolo Abeni --- net/vmw_vsock/af_vsock.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 74d35a8716446..fa9d1b49599bf 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -879,6 +879,9 @@ EXPORT_SYMBOL_GPL(vsock_create_connected); s64 vsock_stream_has_data(struct vsock_sock *vsk) { + if (WARN_ON(!vsk->transport)) + return 0; + return vsk->transport->stream_has_data(vsk); } EXPORT_SYMBOL_GPL(vsock_stream_has_data); @@ -887,6 +890,9 @@ s64 vsock_connectible_has_data(struct vsock_sock *vsk) { struct sock *sk = sk_vsock(vsk); + if (WARN_ON(!vsk->transport)) + return 0; + if (sk->sk_type == SOCK_SEQPACKET) return vsk->transport->seqpacket_has_data(vsk); else @@ -896,6 +902,9 @@ EXPORT_SYMBOL_GPL(vsock_connectible_has_data); s64 vsock_stream_has_space(struct vsock_sock *vsk) { + if (WARN_ON(!vsk->transport)) + return 0; + return vsk->transport->stream_has_space(vsk); } EXPORT_SYMBOL_GPL(vsock_stream_has_space);