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Tsirkin" To: Stefano Garzarella Cc: netdev@vger.kernel.org, Simon Horman , Stefan Hajnoczi , linux-kernel@vger.kernel.org, Eric Dumazet , Xuan Zhuo , Wongi Lee , "David S. Miller" , Paolo Abeni , Jason Wang , Bobby Eshleman , virtualization@lists.linux.dev, Eugenio =?iso-8859-1?Q?P=E9rez?= , Luigi Leonardi , bpf@vger.kernel.org, Jakub Kicinski , Hyunwoo Kim , Michal Luczaj , kvm@vger.kernel.org Subject: Re: [PATCH net 2/2] vsock/bpf: return early if transport is not assigned Message-ID: <20250109040628-mutt-send-email-mst@kernel.org> References: <20250108180617.154053-1-sgarzare@redhat.com> <20250108180617.154053-3-sgarzare@redhat.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250108180617.154053-3-sgarzare@redhat.com> On Wed, Jan 08, 2025 at 07:06:17PM +0100, Stefano Garzarella wrote: > 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") > Reported-by: Michal Luczaj > Closes: https://lore.kernel.org/netdev/5ca20d4c-1017-49c2-9516-f6f75fd331e9@rbox.co/ > Signed-off-by: Stefano Garzarella Acked-by: Michael S. Tsirkin > --- > 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); > > -- > 2.47.1