Michael S. Tsirkin
2023-Feb-15 11:45 UTC
[PATCH] vhost-vdpa: cleanup memory maps when closing vdpa fds
On Wed, Feb 15, 2023 at 01:15:55PM +0800, Longpeng (Mike, Cloud Infrastructure Service Product Dept.) wrote:> > > ? 2023/2/15 10:56, Jason Wang ??: > > On Wed, Feb 15, 2023 at 10:49 AM Longpeng (Mike, Cloud Infrastructure > > Service Product Dept.) <longpeng2 at huawei.com> wrote: > > > > > > > > > > > > ? 2023/2/15 10:00, Jason Wang ??: > > > > On Tue, Feb 14, 2023 at 2:28 PM Longpeng (Mike, Cloud Infrastructure > > > > Service Product Dept.) <longpeng2 at huawei.com> wrote: > > > > > > > > > > > > > > > > > > > > ? 2023/2/14 14:16, Jason Wang ??: > > > > > > > > > > > > ? 2023/1/31 22:53, Longpeng(Mike) ??: > > > > > > > From: Longpeng <longpeng2 at huawei.com> > > > > > > > > > > > > > > We must cleanup all memory maps when closing the vdpa fds, otherwise > > > > > > > some critical resources (e.g. memory, iommu map) will leaked if the > > > > > > > userspace exits unexpectedly (e.g. kill -9). > > > > > > > > > > > > > > > > > > Sounds like a bug of the kernel, should we fix there? > > > > > > > > > > > > > > > > For example, the iommu map is setup when QEMU calls VHOST_IOTLB_UPDATE > > > > > ioctl and it'll be freed if QEMU calls VHOST_IOTLB_INVALIDATE ioctl. > > > > > > > > > > So maybe we release these resources in vdpa framework in kernel is a > > > > > suitable choice? > > > > > > > > I think I need understand what does "resources" mean here: > > > > > > > > For iommu mapping, it should be freed by vhost_vdpa_free_domain() in > > > > vhost_vdpa_release()? > > > > > > > > > > Please consider the following lifecycle of the vdpa device: > > > > > > 1. vhost_vdpa_open > > > vhost_vdpa_alloc_domain > > > > > > 2. vhost_vdpa_pa_map > > > pin_user_pages > > > vhost_vdpa_map > > > iommu_map > > > > > > 3. kill QEMU > > > > > > 4. vhost_vdpa_release > > > vhost_vdpa_free_domain > > > > > > In this case, we have no opportunity to invoke unpin_user_pages or > > > iommu_unmap to free the memory. > > > > We do: > > > > vhost_vdpa_cleanup() > > vhost_vdpa_remove_as() > > vhost_vdpa_iotlb_unmap() > > vhost_vdpa_pa_unmap() > > unpin_user_pages() > > vhost_vdpa_general_unmap() > > iommu_unmap() > > ? > > > Oh, my codebase is linux-6.2-rc2 and the commit c070c1912a8 (vhost-vdpa: fix > an iotlb memory leak) already fixed this bug in linux-6.2-rc3. > > > Btw, it looks like we should call vhost_vdpa_free_domain() *after* > > vhost_vdpa_cleanup() otherwise it's a UAF? > > > I think so, the v->domain is set to NULL in vhost_vdpa_free_domain(), it > seems would trigger null-pointer access in my case.OK I'll drop this patch for now then?> > Thanks > > > > > > > > > static int vhost_vdpa_release(struct inode *inode, struct file *filep) > > > > { > > > > struct vhost_vdpa *v = filep->private_data; > > > > struct vhost_dev *d = &v->vdev; > > > > > > > > mutex_lock(&d->mutex); > > > > filep->private_data = NULL; > > > > vhost_vdpa_clean_irq(v); > > > > vhost_vdpa_reset(v); > > > > vhost_dev_stop(&v->vdev); > > > > vhost_vdpa_free_domain(v); > > > > vhost_vdpa_config_put(v); > > > > vhost_vdpa_cleanup(v); > > > > mutex_unlock(&d->mutex); > > > > > > > > atomic_dec(&v->opened); > > > > complete(&v->completion); > > > > > > > > return 0; > > > > } > > > > > > > > > > > > > > By the way, Jason, can you reproduce the problem in your machine? > > > > > > > > > > > > > Haven't got time in doing this but it should be the responsibility of > > > > the author to validate this anyhow. > > > > > > > > Thanks > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Longpeng <longpeng2 at huawei.com> > > > > > > > --- > > > > > > > drivers/vhost/vdpa.c | 13 +++++++++++++ > > > > > > > 1 file changed, 13 insertions(+) > > > > > > > > > > > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > > > > > > index a527eeeac637..37477cffa5aa 100644 > > > > > > > --- a/drivers/vhost/vdpa.c > > > > > > > +++ b/drivers/vhost/vdpa.c > > > > > > > @@ -823,6 +823,18 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v, > > > > > > > vhost_vdpa_remove_as(v, asid); > > > > > > > } > > > > > > > +static void vhost_vdpa_clean_map(struct vhost_vdpa *v) > > > > > > > +{ > > > > > > > + struct vhost_vdpa_as *as; > > > > > > > + u32 asid; > > > > > > > + > > > > > > > + for (asid = 0; asid < v->vdpa->nas; asid++) { > > > > > > > + as = asid_to_as(v, asid); > > > > > > > + if (as) > > > > > > > + vhost_vdpa_unmap(v, &as->iotlb, 0ULL, 0ULL - 1); > > > > > > > + } > > > > > > > +} > > > > > > > + > > > > > > > static int vhost_vdpa_va_map(struct vhost_vdpa *v, > > > > > > > struct vhost_iotlb *iotlb, > > > > > > > u64 iova, u64 size, u64 uaddr, u32 perm) > > > > > > > @@ -1247,6 +1259,7 @@ static int vhost_vdpa_release(struct inode > > > > > > > *inode, struct file *filep) > > > > > > > vhost_vdpa_clean_irq(v); > > > > > > > vhost_vdpa_reset(v); > > > > > > > vhost_dev_stop(&v->vdev); > > > > > > > + vhost_vdpa_clean_map(v); > > > > > > > vhost_vdpa_free_domain(v); > > > > > > > vhost_vdpa_config_put(v); > > > > > > > vhost_vdpa_cleanup(v); > > > > > > > > > > > > . > > > > > > > > > > > > > . > > > > > > > .