Messages in this thread | | | Date | Wed, 15 Feb 2023 13:15:55 +0800 | Subject | Re: [PATCH] vhost-vdpa: cleanup memory maps when closing vdpa fds | From | "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" <> |
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在 2023/2/15 10:56, Jason Wang 写道: > On Wed, Feb 15, 2023 at 10:49 AM Longpeng (Mike, Cloud Infrastructure > Service Product Dept.) <longpeng2@huawei.com> wrote: >> >> >> >> 在 2023/2/15 10:00, Jason Wang 写道: >>> On Tue, Feb 14, 2023 at 2:28 PM Longpeng (Mike, Cloud Infrastructure >>> Service Product Dept.) <longpeng2@huawei.com> wrote: >>>> >>>> >>>> >>>> 在 2023/2/14 14:16, Jason Wang 写道: >>>>> >>>>> 在 2023/1/31 22:53, Longpeng(Mike) 写道: >>>>>> From: Longpeng <longpeng2@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.
> 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@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); >>>>> >>>>> . >>>> >>> >>> . >> > > .
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