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 mhal@rbox.co Closes: https://lore.kernel.org/netdev/5ca20d4c-1017-49c2-9516-f6f75fd331e9@rbox.co/ Tested-by: Michal Luczaj mhal@rbox.co 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 v4bel@theori.io Acked-by: Michael S. Tsirkin mst@redhat.com Reviewed-by: Luigi Leonardi leonardi@redhat.com Signed-off-by: Stefano Garzarella sgarzare@redhat.com --- 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 4aa6e74ec295..f201d9eca1df 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);