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Tsirkin" , Claude Code , Sasha Levin Subject: [PATCH 6.1.y] vduse: fix VA/PA confusion in the coherent page fault path Date: Sat, 14 Nov 2026 10:19:55 -0500 Message-ID: <20261114151931.3517070-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109201745-failed-6.1-bb2e6f166547@kernel.org> References: <20261109201745-failed-6.1-bb2e6f166547@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "chenglong.ma" [ Upstream commit bb2e6f166547838fd7c320b01c90918b736f76e2 ] 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: 8c773d53fb7b ("vduse: Implement an MMU-based software IOTLB") Cc: Xie Yongji Cc: stable@vger.kernel.org Reported-by: chenglong.ma Signed-off-by: chenglong.ma Signed-off-by: Michael S. Tsirkin Co-Authored-By: Claude Code [ sashal: replaced vm_flags_set() with a direct vma->vm_flags |= update because the helper is unavailable ] Signed-off-by: Sasha Levin --- drivers/vdpa/vdpa_user/iova_domain.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c index e60a2b4065af9..a0c6835019a63 100644 --- a/drivers/vdpa/vdpa_user/iova_domain.c +++ b/drivers/vdpa/vdpa_user/iova_domain.c @@ -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, @@ -222,6 +226,7 @@ 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; @@ -230,6 +235,10 @@ 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: @@ -565,7 +574,7 @@ static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma) { struct vduse_iova_domain *domain = file->private_data; - vma->vm_flags |= VM_DONTDUMP | VM_DONTEXPAND; + vma->vm_flags |= VM_IO | VM_DONTDUMP | VM_DONTEXPAND; vma->vm_private_data = domain; vma->vm_ops = &vduse_domain_mmap_ops; -- 2.53.0