Re: [PATCH net 2/2] vsock/bpf: return early if transport is not assigned
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2025-01-09 09:07:14
Also in:
bpf, kvm, lkml, virtualization
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 <redacted>
Closes: https://lore.kernel.org/netdev/5ca20d4c-1017-49c2-9516-f6f75fd331e9@rbox.co/ (local)
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>Acked-by: Michael S. Tsirkin <mst@redhat.com>
quoted hunk ↗ jump to hunk
--- 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