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Subject[PATCH net 2/2] vhost: fix ubuf_info cleanup
vhost_net_clear_ubuf_info didn't clear ubuf_info
after kfree, this could trigger double free.
Fix this and simplify this code to make it more robust: make sure
ubuf info is always freed through vhost_net_clear_ubuf_info.

Reported-by: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/net.c | 22 +++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 6b00f64..7fc47f7 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -155,14 +155,11 @@ static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)

static void vhost_net_clear_ubuf_info(struct vhost_net *n)
{
-
- bool zcopy;
int i;

- for (i = 0; i < n->dev.nvqs; ++i) {
- zcopy = vhost_net_zcopy_mask & (0x1 << i);
- if (zcopy)
- kfree(n->vqs[i].ubuf_info);
+ for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+ kfree(n->vqs[i].ubuf_info);
+ n->vqs[i].ubuf_info = NULL;
}
}

@@ -171,7 +168,7 @@ int vhost_net_set_ubuf_info(struct vhost_net *n)
bool zcopy;
int i;

- for (i = 0; i < n->dev.nvqs; ++i) {
+ for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
zcopy = vhost_net_zcopy_mask & (0x1 << i);
if (!zcopy)
continue;
@@ -183,12 +180,7 @@ int vhost_net_set_ubuf_info(struct vhost_net *n)
return 0;

err:
- while (i--) {
- zcopy = vhost_net_zcopy_mask & (0x1 << i);
- if (!zcopy)
- continue;
- kfree(n->vqs[i].ubuf_info);
- }
+ vhost_net_clear_ubuf_info(n);
return -ENOMEM;
}

@@ -196,12 +188,12 @@ void vhost_net_vq_reset(struct vhost_net *n)
{
int i;

+ vhost_net_clear_ubuf_info(n);
+
for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
n->vqs[i].done_idx = 0;
n->vqs[i].upend_idx = 0;
n->vqs[i].ubufs = NULL;
- kfree(n->vqs[i].ubuf_info);
- n->vqs[i].ubuf_info = NULL;
n->vqs[i].vhost_hlen = 0;
n->vqs[i].sock_hlen = 0;
}
--
MST


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