[RFC PATCH] vhost_vdpa: assign irq bypass producer token correctly
From: Jason Wang <jasowang@redhat.com>
Date: 2024-08-08 08:20:57
Also in:
kvm, lkml, virtualization
Subsystem:
the rest, virtio host (vhost) · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
We used to call irq_bypass_unregister_producer() in
vhost_vdpa_setup_vq_irq() which is problematic as we don't know if the
token pointer is still valid or not.
Actually, we use the eventfd_ctx as the token so the life cycle of the
token should be bound to the VHOST_SET_VRING_CALL instead of
vhost_vdpa_setup_vq_irq() which could be called by set_status().
Fixing this by setting up irq bypass producer's token when handling
VHOST_SET_VRING_CALL and un-registering the producer before calling
vhost_vring_ioctl() to prevent a possible use after free as eventfd
could have been released in vhost_vring_ioctl().
Fixes: 2cf1ba9a4d15 ("vhost_vdpa: implement IRQ offloading in vhost_vdpa")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
Note for Dragos: Please check whether this fixes your issue. I
slightly test it with vp_vdpa in L2.
---
drivers/vhost/vdpa.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index e31ec9ebc4ce..388226a48bcc 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c@@ -209,11 +209,9 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid) if (irq < 0) return; - irq_bypass_unregister_producer(&vq->call_ctx.producer); if (!vq->call_ctx.ctx) return; - vq->call_ctx.producer.token = vq->call_ctx.ctx; vq->call_ctx.producer.irq = irq; ret = irq_bypass_register_producer(&vq->call_ctx.producer); if (unlikely(ret))
@@ -709,6 +707,12 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, vq->last_avail_idx = vq_state.split.avail_index; } break; + case VHOST_SET_VRING_CALL: + if (vq->call_ctx.ctx) { + vhost_vdpa_unsetup_vq_irq(v, idx); + vq->call_ctx.producer.token = NULL; + } + break; } r = vhost_vring_ioctl(&v->vdev, cmd, argp);
@@ -747,13 +751,14 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, cb.callback = vhost_vdpa_virtqueue_cb; cb.private = vq; cb.trigger = vq->call_ctx.ctx; + vq->call_ctx.producer.token = vq->call_ctx.ctx; + vhost_vdpa_setup_vq_irq(v, idx); } else { cb.callback = NULL; cb.private = NULL; cb.trigger = NULL; } ops->set_vq_cb(vdpa, idx, &cb); - vhost_vdpa_setup_vq_irq(v, idx); break; case VHOST_SET_VRING_NUM:
@@ -1419,6 +1424,7 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep) for (i = 0; i < nvqs; i++) { vqs[i] = &v->vqs[i]; vqs[i]->handle_kick = handle_vq_kick; + vqs[i]->call_ctx.ctx = NULL; } vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false, vhost_vdpa_process_iotlb_msg);
--
2.31.1