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| author | Robin Murphy <robin.murphy@arm.com> | 2019-07-29 17:46:00 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-06 10:19:41 +0200 |
| commit | 10f13d9804080db737f0b5678ac202fcbbf8e1be (patch) | |
| tree | 2313f1f59d8af6f85734a374bdfea270339f4d90 /drivers/iommu | |
| parent | 7900374c9a93f515f2ff9826bee02dd533c334e5 (diff) | |
iommu/dma: Handle SG length overflow better
[ Upstream commit ab2cbeb0ed301a9f0460078e91b09f39958212ef ]
Since scatterlist dimensions are all unsigned ints, in the relatively
rare cases where a device's max_segment_size is set to UINT_MAX, then
the "cur_len + s_length <= max_len" check in __finalise_sg() will always
return true. As a result, the corner case of such a device mapping an
excessively large scatterlist which is mergeable to or beyond a total
length of 4GB can lead to overflow and a bogus truncated dma_length in
the resulting segment.
As we already assume that any single segment must be no longer than
max_len to begin with, this can easily be addressed by reshuffling the
comparison.
Fixes: 809eac54cdd6 ("iommu/dma: Implement scatterlist segment merging")
Reported-by: Nicolin Chen <nicoleotsuka@gmail.com>
Tested-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/iommu')
| -rw-r--r-- | drivers/iommu/dma-iommu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 1520e7f02c2f..89d191b6a0e0 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -493,7 +493,7 @@ static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents, * - and wouldn't make the resulting output segment too long */ if (cur_len && !s_iova_off && (dma_addr & seg_mask) && - (cur_len + s_length <= max_len)) { + (max_len - cur_len >= s_length)) { /* ...then concatenate it with the previous one */ cur_len += s_length; } else { |