diff options
author | Ralph Campbell <rcampbell@nvidia.com> | 2019-08-24 01:17:53 +0300 |
---|---|---|
committer | Jason Gunthorpe <jgg@mellanox.com> | 2019-08-28 01:27:07 +0300 |
commit | c18ce674d548c00faa6b7e760bacbaf1f39315f3 (patch) | |
tree | 33ca4bae9d6c21f40ba4a095fb80294c968943eb /mm | |
parent | 6c64f2bbe79cf3b770ac60ae79442322bd76d55e (diff) | |
download | linux-c18ce674d548c00faa6b7e760bacbaf1f39315f3.tar.xz |
mm/hmm: hmm_range_fault() infinite loop
Normally, callers to handle_mm_fault() are supposed to check the
vma->vm_flags first. hmm_range_fault() checks for VM_READ but doesn't
check for VM_WRITE if the caller requests a page to be faulted in with
write permission (via the hmm_range.pfns[] value). If the vma is write
protected, this can result in an infinite loop:
hmm_range_fault()
walk_page_range()
...
hmm_vma_walk_hole()
hmm_vma_walk_hole_()
hmm_vma_do_fault()
handle_mm_fault(FAULT_FLAG_WRITE)
/* returns VM_FAULT_WRITE */
/* returns -EBUSY */
/* returns -EBUSY */
/* returns -EBUSY */
/* loops on -EBUSY and range->valid */
Prevent this by checking for vma->vm_flags & VM_WRITE before calling
handle_mm_fault().
Link: https://lore.kernel.org/r/20190823221753.2514-3-rcampbell@nvidia.com
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/hmm.c | 3 |
1 files changed, 3 insertions, 0 deletions
@@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end, hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; + if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE)) + return -EPERM; + for (; addr < end; addr += PAGE_SIZE, i++) { pfns[i] = range->values[HMM_PFN_NONE]; if (fault || write_fault) { |