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([5.77.78.183]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a8e38332asm3858150f8f.23.2025.01.10.00.35.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jan 2025 00:35:26 -0800 (PST) From: Stefano Garzarella To: netdev@vger.kernel.org Cc: Xuan Zhuo , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Luigi Leonardi , "David S. Miller" , Wongi Lee , Stefano Garzarella , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , "Michael S. Tsirkin" , Eric Dumazet , kvm@vger.kernel.org, Paolo Abeni , Stefan Hajnoczi , Jason Wang , Simon Horman , Hyunwoo Kim , Jakub Kicinski , Michal Luczaj , virtualization@lists.linux.dev, Bobby Eshleman , stable@vger.kernel.org, syzbot+3affdbfc986ecd9200fd@syzkaller.appspotmail.com Subject: [PATCH net v2 2/5] vsock/bpf: return early if transport is not assigned Date: Fri, 10 Jan 2025 09:35:08 +0100 Message-ID: <20250110083511.30419-3-sgarzare@redhat.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250110083511.30419-1-sgarzare@redhat.com> References: <20250110083511.30419-1-sgarzare@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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@go= ogle.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 --- 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 msgh= dr *msg, size_t len, int flags, int *addr_len) { struct sk_psock *psock; + struct vsock_sock *vsk; int copied; =20 psock =3D sk_psock_get(sk); @@ -84,6 +85,13 @@ static int vsock_bpf_recvmsg(struct sock *sk, struct msg= hdr *msg, return __vsock_recvmsg(sk, msg, len, flags); =20 lock_sock(sk); + vsk =3D vsock_sk(sk); + + if (!vsk->transport) { + copied =3D -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 ms= ghdr *msg, copied =3D sk_msg_recvmsg(sk, psock, msg, len, flags); } =20 +out: release_sock(sk); sk_psock_put(sk, psock); =20 --=20 2.47.1