Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 5 May 2024 22:53:39 +0300 | From | Arseniy Krasnov <> | Subject | Re: [PATCH virt] virt: fix uninit-value in vhost_vsock_dev_open |
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> But now that it's explained, the bugfix as proposed is incomplete: > userspace can set features twice and the second time will leak > old VIRTIO_VSOCK_F_SEQPACKET bit value. > > And I am pretty sure the Fixes tag is wrong. > > So I wrote this, but I actually don't have a set for > seqpacket to test this. Arseny could you help test maybe? > Thanks!
Hi! Sorry for late reply! Just run vsock test suite with this patch - seems everything is ok!
> > > commit bcc17a060d93b198d8a17a9b87b593f41337ee28 > Author: Michael S. Tsirkin <mst@redhat.com> > Date: Mon Apr 22 10:03:13 2024 -0400 > > vhost/vsock: always initialize seqpacket_allow > > There are two issues around seqpacket_allow: > 1. seqpacket_allow is not initialized when socket is > created. Thus if features are never set, it will be > read uninitialized. > 2. if VIRTIO_VSOCK_F_SEQPACKET is set and then cleared, > then seqpacket_allow will not be cleared appropriately > (existing apps I know about don't usually do this but > it's legal and there's no way to be sure no one relies > on this). > > To fix: > - initialize seqpacket_allow after allocation > - set it unconditionally in set_features > > Reported-by: syzbot+6c21aeb59d0e82eb2782@syzkaller.appspotmail.com > Reported-by: Jeongjun Park <aha310510@gmail.com> > Fixes: ced7b713711f ("vhost/vsock: support SEQPACKET for transport"). > Cc: Arseny Krasnov <arseny.krasnov@kaspersky.com> > Cc: David S. Miller <davem@davemloft.net> > Cc: Stefan Hajnoczi <stefanha@redhat.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
> > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c > index ec20ecff85c7..bf664ec9341b 100644 > --- a/drivers/vhost/vsock.c > +++ b/drivers/vhost/vsock.c > @@ -667,6 +667,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file) > } > > vsock->guest_cid = 0; /* no CID assigned yet */ > + vsock->seqpacket_allow = false; > > atomic_set(&vsock->queued_replies, 0); > > @@ -810,8 +811,7 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features) > goto err; > } > > - if (features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET)) > - vsock->seqpacket_allow = true; > + vsock->seqpacket_allow = features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET); > > for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) { > vq = &vsock->vqs[i];
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