mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-18 22:14:16 +00:00
dd54bcf86c
When operating on struct vhost_net_ubuf_ref, the following execution
sequence is theoretically possible:
CPU0 is finalizing DMA operation CPU1 is doing VHOST_NET_SET_BACKEND
// ubufs->refcount == 2
vhost_net_ubuf_put() vhost_net_ubuf_put_wait_and_free(oldubufs)
vhost_net_ubuf_put_and_wait()
vhost_net_ubuf_put()
int r = atomic_sub_return(1, &ubufs->refcount);
// r = 1
int r = atomic_sub_return(1, &ubufs->refcount);
// r = 0
wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
// no wait occurs here because condition is already true
kfree(ubufs);
if (unlikely(!r))
wake_up(&ubufs->wait); // use-after-free
This leads to use-after-free on ubufs access. This happens because CPU1
skips waiting for wake_up() when refcount is already zero.
To prevent that use a read-side RCU critical section in vhost_net_ubuf_put(),
as suggested by Hillf Danton. For this lock to take effect, free ubufs with
kfree_rcu().
Cc: stable@vger.kernel.org
Fixes:
|
||
|---|---|---|
| .. | ||
| iotlb.c | ||
| Kconfig | ||
| Makefile | ||
| net.c | ||
| scsi.c | ||
| test.c | ||
| test.h | ||
| vdpa.c | ||
| vhost.c | ||
| vhost.h | ||
| vringh.c | ||
| vsock.c | ||