From: Ralph Campbell <rcampbell@nvidia.com>
To: <linux-mm@kvack.org>
Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
"Jérôme Glisse" <jglisse@redhat.com>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Christoph Hellwig" <hch@lst.de>,
"Ralph Campbell" <rcampbell@nvidia.com>
Subject: [PATCH 1/2] mm/hmm: hmm_range_fault() NULL pointer bug
Date: Fri, 23 Aug 2019 15:17:52 -0700 [thread overview]
Message-ID: <20190823221753.2514-2-rcampbell@nvidia.com> (raw)
In-Reply-To: <20190823221753.2514-1-rcampbell@nvidia.com>
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)
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
---
mm/hmm.c | 13 +++++++++----
1 file 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,
--
2.20.1
next prev parent reply other threads:[~2019-08-23 22:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-23 22:17 [PATCH 0/2] mm/hmm: two bug fixes for hmm_range_fault() Ralph Campbell
2019-08-23 22:17 ` Ralph Campbell [this message]
2019-08-24 22:37 ` [PATCH 1/2] mm/hmm: hmm_range_fault() NULL pointer bug Christoph Hellwig
2019-08-26 18:02 ` Ralph Campbell
2019-08-26 18:09 ` Jason Gunthorpe
2019-08-26 18:21 ` Ralph Campbell
2019-08-23 22:17 ` [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Ralph Campbell
2019-08-24 22:39 ` Christoph Hellwig
2019-08-27 18:41 ` Jason Gunthorpe
2019-08-27 20:16 ` Ralph Campbell
2019-08-27 22:22 ` Jason Gunthorpe
2019-08-27 22:48 ` [PATCH 0/2] mm/hmm: two bug fixes for hmm_range_fault() Jason Gunthorpe
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