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vmmdev: return EFAULT when trying to read beyond VM system memory max address

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Currently, when using dd(1) to take a VM memory image, the capture never ends,
reading zeroes when it's beyond VM system memory max address.
Return EFAULT when trying to read beyond VM system memory max address.

Reviewed by:	imp, grehan, anish
Approved by:	grehan
Differential Revision:	https://reviews.freebsd.org/D15156
This commit is contained in:
Antoine Brodin 2018-05-15 17:20:58 +00:00
parent 7c5ccd2dce
commit 147d12a7d3
3 changed files with 7 additions and 5 deletions
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1
sys/amd64/include/vmm.h
View File

@ -212,6 +212,7 @@ int vm_mmap_getnext(struct vm *vm, vm_paddr_t *gpa, int *segid,
vm_ooffset_t *segoff, size_t *len, int *prot, int *flags);
int vm_get_memseg(struct vm *vm, int ident, size_t *len, bool *sysmem,
struct vm_object **objptr);
vm_paddr_t vmm_sysmem_maxaddr(struct vm *vm);
void *vm_gpa_hold(struct vm *, int vcpuid, vm_paddr_t gpa, size_t len,
int prot, void **cookie);
void vm_gpa_release(void *cookie);

6
sys/amd64/vmm/vmm.c
View File

@ -821,8 +821,8 @@ sysmem_mapping(struct vm *vm, struct mem_map *mm)
return (false);
}
static vm_paddr_t
sysmem_maxaddr(struct vm *vm)
vm_paddr_t
vmm_sysmem_maxaddr(struct vm *vm)
{
struct mem_map *mm;
vm_paddr_t maxaddr;
@ -931,7 +931,7 @@ vm_assign_pptdev(struct vm *vm, int bus, int slot, int func)
if (ppt_assigned_devices(vm) == 0) {
KASSERT(vm->iommu == NULL,
("vm_assign_pptdev: iommu must be NULL"));
maxaddr = sysmem_maxaddr(vm);
maxaddr = vmm_sysmem_maxaddr(vm);
vm->iommu = iommu_create_domain(maxaddr);
if (vm->iommu == NULL)
return (ENXIO);

5
sys/amd64/vmm/vmm_dev.c
View File

@ -173,7 +173,7 @@ static int
vmmdev_rw(struct cdev *cdev, struct uio *uio, int flags)
{
int error, off, c, prot;
vm_paddr_t gpa;
vm_paddr_t gpa, maxaddr;
void *hpa, *cookie;
struct vmmdev_softc *sc;
@ -189,6 +189,7 @@ vmmdev_rw(struct cdev *cdev, struct uio *uio, int flags)
return (error);
prot = (uio->uio_rw == UIO_WRITE ? VM_PROT_WRITE : VM_PROT_READ);
maxaddr = vmm_sysmem_maxaddr(sc->vm);
while (uio->uio_resid > 0 && error == 0) {
gpa = uio->uio_offset;
off = gpa & PAGE_MASK;
@ -204,7 +205,7 @@ vmmdev_rw(struct cdev *cdev, struct uio *uio, int flags)
*/
hpa = vm_gpa_hold(sc->vm, VM_MAXCPU - 1, gpa, c, prot, &cookie);
if (hpa == NULL) {
if (uio->uio_rw == UIO_READ)
if (uio->uio_rw == UIO_READ && gpa < maxaddr)
error = uiomove(__DECONST(void *, zero_region),
c, uio);
else