vhost_net_ubuf_put_and_wait has a confusing name:
it will actually also free it's argument.
Thus since commit 1280c27f8e29acf4af2da914e80ec27c3dbd5c01
vhost_net_flush tries to use the argument after passing it
to vhost_net_ubuf_put_and_wait, this results
in use after free.
To fix, don't free the argument in vhost_net_ubuf_put_and_wait,
add an new API for callers that want to free ubufs.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
I sent the same patch against 3.10 separately.
This one is for stable, against 3.9/3.8 - the code moved around
since then.
Not sending to stable directly since Dave Miller handles
it for net drivers normally.
drivers/vhost/net.c | 4 ++--
drivers/vhost/vhost.c | 5 +++++
drivers/vhost/vhost.h | 1 +
3 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index ec6fb3f..e5ff7a5 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -856,7 +856,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
mutex_unlock(&vq->mutex);
if (oldubufs) {
- vhost_ubuf_put_and_wait(oldubufs);
+ vhost_ubuf_put_wait_and_free(oldubufs);
mutex_lock(&vq->mutex);
vhost_zerocopy_signal_used(n, vq);
mutex_unlock(&vq->mutex);
@@ -874,7 +874,7 @@ err_used:
rcu_assign_pointer(vq->private_data, oldsock);
vhost_net_enable_vq(n, vq);
if (ubufs)
- vhost_ubuf_put_and_wait(ubufs);
+ vhost_ubuf_put_wait_and_free(ubufs);
err_ubufs:
fput(sock->file);
err_vq:
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9759249..c01d22f 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1581,5 +1581,10 @@ void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs)
{
kref_put(&ubufs->kref, vhost_zerocopy_done_signal);
wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
+}
+
+void vhost_ubuf_put_wait_and_free(struct vhost_ubuf_ref *ubufs)
+{
+ vhost_ubuf_put_and_wait(ubufs);
kfree(ubufs);
}
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 17261e2..b53cb28 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -63,6 +63,7 @@ struct vhost_ubuf_ref {
struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
void vhost_ubuf_put(struct vhost_ubuf_ref *);
void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
+void vhost_ubuf_put_wait_and_free(struct vhost_ubuf_ref *);
struct ubuf_info;
--
MST
--
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