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Subject[PATCH net 1/2] vsock/virtio: fix null-pointer dereference in virtio_transport_recv_listen()
Date
With multi-transport support, listener sockets are not bound to any
transport. So, calling virtio_transport_reset(), when an error
occurs, on a listener socket produces the following null-pointer
dereference:

BUG: kernel NULL pointer dereference, address: 00000000000000e8
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 20 Comm: kworker/0:1 Not tainted 5.5.0-rc1-ste-00003-gb4be21f316ac-dirty #56
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
Workqueue: virtio_vsock virtio_transport_rx_work [vmw_vsock_virtio_transport]
RIP: 0010:virtio_transport_send_pkt_info+0x20/0x130 [vmw_vsock_virtio_transport_common]
Code: 1f 84 00 00 00 00 00 0f 1f 00 55 48 89 e5 41 57 41 56 41 55 49 89 f5 41 54 49 89 fc 53 48 83 ec 10 44 8b 76 20 e8 c0 ba fe ff <48> 8b 80 e8 00 00 00 e8 64 e3 7d c1 45 8b 45 00 41 8b 8c 24 d4 02
RSP: 0018:ffffc900000b7d08 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88807bf12728 RCX: 0000000000000000
RDX: ffff88807bf12700 RSI: ffffc900000b7d50 RDI: ffff888035c84000
RBP: ffffc900000b7d40 R08: ffff888035c84000 R09: ffffc900000b7d08
R10: ffff8880781de800 R11: 0000000000000018 R12: ffff888035c84000
R13: ffffc900000b7d50 R14: 0000000000000000 R15: ffff88807bf12724
FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000000e8 CR3: 00000000790f4004 CR4: 0000000000160ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
virtio_transport_reset+0x59/0x70 [vmw_vsock_virtio_transport_common]
virtio_transport_recv_pkt+0x5bb/0xe50 [vmw_vsock_virtio_transport_common]
? detach_buf_split+0xf1/0x130
virtio_transport_rx_work+0xba/0x130 [vmw_vsock_virtio_transport]
process_one_work+0x1c0/0x300
worker_thread+0x45/0x3c0
kthread+0xfc/0x130
? current_work+0x40/0x40
? kthread_park+0x90/0x90
ret_from_fork+0x35/0x40
Modules linked in: sunrpc kvm_intel kvm vmw_vsock_virtio_transport vmw_vsock_virtio_transport_common irqbypass vsock virtio_rng rng_core
CR2: 00000000000000e8
---[ end trace e75400e2ea2fa824 ]---

This happens because virtio_transport_reset() calls
virtio_transport_send_pkt_info() that can be used only on
connecting/connected sockets.

This patch fixes the issue, using virtio_transport_reset_no_sock()
instead of virtio_transport_reset() when we are handling a listener
socket.

Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
net/vmw_vsock/virtio_transport_common.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index e5ea29c6bca7..f5991006190e 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1021,18 +1021,18 @@ virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
int ret;

if (le16_to_cpu(pkt->hdr.op) != VIRTIO_VSOCK_OP_REQUEST) {
- virtio_transport_reset(vsk, pkt);
+ virtio_transport_reset_no_sock(t, pkt);
return -EINVAL;
}

if (sk_acceptq_is_full(sk)) {
- virtio_transport_reset(vsk, pkt);
+ virtio_transport_reset_no_sock(t, pkt);
return -ENOMEM;
}

child = vsock_create_connected(sk);
if (!child) {
- virtio_transport_reset(vsk, pkt);
+ virtio_transport_reset_no_sock(t, pkt);
return -ENOMEM;
}

@@ -1054,7 +1054,7 @@ virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
*/
if (ret || vchild->transport != &t->transport) {
release_sock(child);
- virtio_transport_reset(vsk, pkt);
+ virtio_transport_reset_no_sock(t, pkt);
sock_put(child);
return ret;
}
--
2.23.0
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