From nobody Sun Feb 8 11:26:08 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D778171072 for ; Wed, 10 Apr 2024 15:56:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712764566; cv=none; b=OXUIswY8GQFVgjVGZuh2OO4RJhRC0XS9H8wTPc1umMpDrNNLw+RFtBf6/xTRDz27aDSiYOOoGDSQqWftOAnFyP/8Qpuyn7HTb3FfAfxfN+zFKVCOqagp2lbFQsXz6hYH5xNWgSO/l3cxXo7cR95Uav8N4HxHhKCY7wYb699SFQY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712764566; c=relaxed/simple; bh=iEy3Y/wQo4siK0uRbJbPEGBhTif0nXoV2Vtkal8J/KM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dwc2V2HUZutbiF0D34zS9jYgQqtq4xNk5k+AUnu/HYS1SVGhD0TOlaCF4X4krGOk3kHDgQ9BWiyix+xasyN7rj6QgHOznUDmq6xaRka2PoY9PlZaCK8KP8EksZNpS+7o4f1DvMoQ53ceFRBOnv+CYo4rw2AruxdndzVa0hHIpBE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=R6mOtYo2; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R6mOtYo2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712764563; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EdXXvnzyQGyp+LpfjwfWgygVrfKZBZQWfHJtEeA5yjk=; b=R6mOtYo2FE6gjnIEAXu5FpESXWSVEBEHIsLqQhYMUDjm5Y7TEXSP2J7FheeLA/eNVMGD07 ZdhHFqqLpnavzc93dASylLgUqkApGt3il8cApjxIHj25xoXxln/vEgSCsvGaKygNTlAFbO gfnTrnMce1IPi/CWiRL9kHPb+2bZZ/o= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-369-QFt8f6HZNKShSzTznoalRA-1; Wed, 10 Apr 2024 11:55:57 -0400 X-MC-Unique: QFt8f6HZNKShSzTznoalRA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 38C151805BE0; Wed, 10 Apr 2024 15:55:56 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.193.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id C8CE72DD51; Wed, 10 Apr 2024 15:55:52 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, David Hildenbrand , Andrew Morton , Yonghua Huang , Fei Li , Christoph Hellwig , Gerald Schaefer , Heiko Carstens , Ingo Molnar , Alex Williamson , Paolo Bonzini Subject: [PATCH v1 1/3] drivers/virt/acrn: fix PFNMAP PTE checks in acrn_vm_ram_map() Date: Wed, 10 Apr 2024 17:55:25 +0200 Message-ID: <20240410155527.474777-2-david@redhat.com> In-Reply-To: <20240410155527.474777-1-david@redhat.com> References: <20240410155527.474777-1-david@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Content-Type: text/plain; charset="utf-8" We currently miss to handle various cases, resulting in a dangerous follow_pte() (previously follow_pfn()) usage. (1) We're not checking PTE write permissions. Maybe we should simply always require pte_write() like we do for pin_user_pages_fast(FOLL_WRITE)? Hard to tell, so let's check for ACRN_MEM_ACCESS_WRITE for now. (2) We're not rejecting refcounted pages. As we are not using MMU notifiers, messing with refcounted pages is dangerous and can result in use-after-free. Let's make sure to reject them. (3) We are only looking at the first PTE of a bigger range. We only lookup a single PTE, but memmap->len may span a larger area. Let's loop over all involved PTEs and make sure the PFN range is actually contiguous. Reject everything else: it couldn't have worked either way, and rather made use access PFNs we shouldn't be accessing. Fixes: 8a6e85f75a83 ("virt: acrn: obtain pa from VMA with PFNMAP flag") Signed-off-by: David Hildenbrand Reviewed-by: David Hildenbrand --- drivers/virt/acrn/mm.c | 63 +++++++++++++++++++++++++++++++----------- 1 file changed, 47 insertions(+), 16 deletions(-) diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c index b30077baf352..2d98e1e185c4 100644 --- a/drivers/virt/acrn/mm.c +++ b/drivers/virt/acrn/mm.c @@ -156,23 +156,29 @@ int acrn_vm_memseg_unmap(struct acrn_vm *vm, struct a= crn_vm_memmap *memmap) int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap) { struct vm_memory_region_batch *regions_info; - int nr_pages, i =3D 0, order, nr_regions =3D 0; + int nr_pages, i, order, nr_regions =3D 0; struct vm_memory_mapping *region_mapping; struct vm_memory_region_op *vm_region; struct page **pages =3D NULL, *page; void *remap_vaddr; int ret, pinned; u64 user_vm_pa; - unsigned long pfn; struct vm_area_struct *vma; =20 if (!vm || !memmap) return -EINVAL; =20 + /* Get the page number of the map region */ + nr_pages =3D memmap->len >> PAGE_SHIFT; + if (!nr_pages) + return -EINVAL; + mmap_read_lock(current->mm); vma =3D vma_lookup(current->mm, memmap->vma_base); if (vma && ((vma->vm_flags & VM_PFNMAP) !=3D 0)) { + unsigned long start_pfn, cur_pfn; spinlock_t *ptl; + bool writable; pte_t *ptep; =20 if ((memmap->vma_base + memmap->len) > vma->vm_end) { @@ -180,25 +186,53 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_v= m_memmap *memmap) return -EINVAL; } =20 - ret =3D follow_pte(vma->vm_mm, memmap->vma_base, &ptep, &ptl); - if (ret < 0) { - mmap_read_unlock(current->mm); + for (i =3D 0; i < nr_pages; i++) { + ret =3D follow_pte(vma->vm_mm, + memmap->vma_base + i * PAGE_SIZE, + &ptep, &ptl); + if (ret) + break; + + cur_pfn =3D pte_pfn(ptep_get(ptep)); + if (i =3D=3D 0) + start_pfn =3D cur_pfn; + writable =3D !!pte_write(ptep_get(ptep)); + pte_unmap_unlock(ptep, ptl); + + /* Disallow write access if the PTE is not writable. */ + if (!writable && + (memmap->attr & ACRN_MEM_ACCESS_WRITE)) { + ret =3D -EFAULT; + break; + } + + /* Disallow refcounted pages. */ + if (pfn_valid(cur_pfn) && + !PageReserved(pfn_to_page(cur_pfn))) { + ret =3D -EFAULT; + break; + } + + /* Disallow non-contiguous ranges. */ + if (cur_pfn !=3D start_pfn + i) { + ret =3D -EINVAL; + break; + } + } + mmap_read_unlock(current->mm); + + if (ret) { dev_dbg(acrn_dev.this_device, "Failed to lookup PFN at VMA:%pK.\n", (void *)memmap->vma_base); return ret; } - pfn =3D pte_pfn(ptep_get(ptep)); - pte_unmap_unlock(ptep, ptl); - mmap_read_unlock(current->mm); =20 return acrn_mm_region_add(vm, memmap->user_vm_pa, - PFN_PHYS(pfn), memmap->len, + PFN_PHYS(start_pfn), memmap->len, ACRN_MEM_TYPE_WB, memmap->attr); } mmap_read_unlock(current->mm); =20 - /* Get the page number of the map region */ - nr_pages =3D memmap->len >> PAGE_SHIFT; pages =3D vzalloc(array_size(nr_pages, sizeof(*pages))); if (!pages) return -ENOMEM; @@ -242,12 +276,11 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_v= m_memmap *memmap) mutex_unlock(&vm->regions_mapping_lock); =20 /* Calculate count of vm_memory_region_op */ - while (i < nr_pages) { + for (i =3D 0; i < nr_pages; i +=3D 1 << order) { page =3D pages[i]; VM_BUG_ON_PAGE(PageTail(page), page); order =3D compound_order(page); nr_regions++; - i +=3D 1 << order; } =20 /* Prepare the vm_memory_region_batch */ @@ -264,8 +297,7 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_= memmap *memmap) regions_info->vmid =3D vm->vmid; regions_info->regions_gpa =3D virt_to_phys(vm_region); user_vm_pa =3D memmap->user_vm_pa; - i =3D 0; - while (i < nr_pages) { + for (i =3D 0; i < nr_pages; i +=3D 1 << order) { u32 region_size; =20 page =3D pages[i]; @@ -281,7 +313,6 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_= memmap *memmap) =20 vm_region++; user_vm_pa +=3D region_size; - i +=3D 1 << order; } =20 /* Inform the ACRN Hypervisor to set up EPT mappings */ --=20 2.44.0