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authorRalph Campbell <rcampbell@nvidia.com>2019-08-24 00:17:52 +0200
committerJason Gunthorpe <jgg@mellanox.com>2019-08-28 00:27:07 +0200
commit6c64f2bbe79cf3b770ac60ae79442322bd76d55e (patch)
tree79acd2366e34348b704a425f07b34e55ebd1ce40 /mm/hmm.c
parentmm/hmm: fix hmm_range_fault()'s handling of swapped out pages (diff)
downloadlinux-6c64f2bbe79cf3b770ac60ae79442322bd76d55e.tar.xz
linux-6c64f2bbe79cf3b770ac60ae79442322bd76d55e.zip
mm/hmm: hmm_range_fault() NULL pointer bug
Although hmm_range_fault() calls find_vma() to make sure that a vma exists before calling walk_page_range(), hmm_vma_walk_hole() can still be called with walk->vma == NULL if the start and end address are not contained within the vma range. hmm_range_fault() /* calls find_vma() but no range check */ walk_page_range() /* calls find_vma(), sets walk->vma = NULL */ __walk_page_range() walk_pgd_range() walk_p4d_range() walk_pud_range() hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(vma=0) Link: https://lore.kernel.org/r/20190823221753.2514-2-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'mm/hmm.c')
-rw-r--r--mm/hmm.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index fc05c8fe78b4..29371485fe94 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -229,6 +229,9 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
struct vm_area_struct *vma = walk->vma;
vm_fault_t ret;
+ if (!vma)
+ goto err;
+
if (hmm_vma_walk->flags & HMM_FAULT_ALLOW_RETRY)
flags |= FAULT_FLAG_ALLOW_RETRY;
if (write_fault)
@@ -239,12 +242,14 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
/* Note, handle_mm_fault did up_read(&mm->mmap_sem)) */
return -EAGAIN;
}
- if (ret & VM_FAULT_ERROR) {
- *pfn = range->values[HMM_PFN_ERROR];
- return -EFAULT;
- }
+ if (ret & VM_FAULT_ERROR)
+ goto err;
return -EBUSY;
+
+err:
+ *pfn = range->values[HMM_PFN_ERROR];
+ return -EFAULT;
}
static int hmm_pfns_bad(unsigned long addr,