[PATCH 4.1 11/86] iommu/amd: Fix BUG when faulting a PROT_NONE VMA

Greg Kroah-Hartman
2015-11-06T20:27:12Z

From: Jay Cornwall <jay@jcornwall.me>

commit d14f6fced5f9360edca5a1325ddb7077aab1203b upstream.

handle_mm_fault indirectly triggers a BUG in do_numa_page
when given a VMA without read/write/execute access. Check
this condition in do_fault.

do_fault -> handle_mm_fault -> handle_pte_fault -> do_numa_page

mm/memory.c
3147 static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
....
3159 /* A PROT_NONE fault should not end up here */
3160 BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));

Signed-off-by: Jay Cornwall <jay@jcornwall.me>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/iommu/amd_iommu_v2.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -508,6 +508,13 @@ static void do_fault(struct work_struct
goto out;
}

+ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) {
+ /* handle_mm_fault would BUG_ON() */
+ up_read(&mm->mmap_sem);
+ handle_fault_error(fault);
+ goto out;
+ }
+
ret = handle_mm_fault(mm, vma, address, write);
if (ret & VM_FAULT_ERROR) {
/* failed to service fault */