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author | Ralph Campbell <rcampbell@nvidia.com> | 2019-08-23 15:17:53 -0700 |
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committer | Jason Gunthorpe <jgg@mellanox.com> | 2019-08-27 19:27:07 -0300 |
commit | c18ce674d548c00faa6b7e760bacbaf1f39315f3 (patch) | |
tree | 33ca4bae9d6c21f40ba4a095fb80294c968943eb /mm/hmm.c | |
parent | 6c64f2bbe79cf3b770ac60ae79442322bd76d55e (diff) | |
download | linux-c18ce674d548c00faa6b7e760bacbaf1f39315f3.tar.gz |
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/hmm.c')
-rw-r--r-- | mm/hmm.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/hmm.c b/mm/hmm.c index 29371485fe94..4882b83aeccb 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -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) { |