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vduse: fix VA/PA confusion in the coherent page fault path

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vduse_domain_get_coherent_page() assumes that iotlb entries above
bounce_size were installed by vduse_domain_alloc_coherent(), so it
treats map->addr as a physical address. But vduse registers with
use_va = true, and when the device is bound to vhost_vdpa,
vhost_vdpa_va_map() stores a userspace virtual address in map->addr,
which vduse_domain_set_map() then copies into the same iotlb. A
process holding the domain file descriptor across a rebind can
therefore fault in an arbitrary physical page with read/write
access, ignoring the entry permissions.

Additionally, since the domain file mmap lacks VM_IO, the domain
file itself can be mapped and passed to vhost_vdpa_va_map(),
producing self-referential entries that bypass the coherent path
check.

To fix, only translate entries whose backing file is the domain
file itself in vduse_domain_get_coherent_page(), reject such
entries in vduse_domain_set_map() since only external mappings
should be imported, and set VM_IO on the domain file mmap so
vhost_vdpa_va_map() refuses to map it in the first place.

Fixes: 8c773d53fb ("vduse: Implement an MMU-based software IOTLB")
Cc: Xie Yongji <xieyongji@bytedance.com>
Cc: stable@vger.kernel.org
Reported-by: chenglong.ma <longpareto@gmail.com>
Signed-off-by: chenglong.ma <longpareto@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Co-Authored-By: Claude Code <noreply@anthropic.com>
This commit is contained in:
chenglong.ma 2026-11-02 12:08:55 -05:00 committed by Michael S. Tsirkin
parent 0f7bf47f5a
commit bb2e6f1665
1 changed files with 10 additions and 1 deletions
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11
drivers/vdpa/vdpa_user/iova_domain.c
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@ -76,6 +76,10 @@ int vduse_domain_set_map(struct vduse_iova_domain *domain,
for (map = vhost_iotlb_itree_first(iotlb, start, last); map;
map = vhost_iotlb_itree_next(map, start, last)) {
map_file = (struct vdpa_map_file *)map->opaque;
if (!map_file || map_file->file == domain->file) {
ret = -EINVAL;
goto err;
}
ret = vduse_iotlb_add_range(domain, map->start, map->last,
map->addr, map->perm,
map_file->file,
@ -226,6 +230,7 @@ vduse_domain_get_coherent_page(struct vduse_iova_domain *domain, u64 iova)
{
u64 start = iova & PAGE_MASK;
u64 last = start + PAGE_SIZE - 1;
struct vdpa_map_file *map_file;
struct vhost_iotlb_map *map;
struct page *page = NULL;
@ -234,6 +239,10 @@ vduse_domain_get_coherent_page(struct vduse_iova_domain *domain, u64 iova)
if (!map)
goto out;
map_file = (struct vdpa_map_file *)map->opaque;
if (!map_file || map_file->file != domain->file)
goto out;
page = pfn_to_page((map->addr + iova - map->start) >> PAGE_SHIFT);
get_page(page);
out:
@ -579,7 +588,7 @@ static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma)
{
struct vduse_iova_domain *domain = file->private_data;
vm_flags_set(vma, VM_DONTDUMP | VM_DONTEXPAND);
vm_flags_set(vma, VM_IO | VM_DONTDUMP | VM_DONTEXPAND);
vma->vm_private_data = domain;
vma->vm_ops = &vduse_domain_mmap_ops;