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| author |   Robin Murphy <robin.murphy@arm.com> | 2019-07-29 17:46:00 +0100 |
|---|---|---|
| committer |   Joerg Roedel <jroedel@suse.de> | 2019-08-09 17:31:39 +0200 |
| commit | ab2cbeb0ed301a9f0460078e91b09f39958212ef (patch) | |
| tree | f63defbae2945d3846f20b852ccde41b9208f1b3 /drivers/iommu | |
| parent | iommu/vt-d: Correctly check format of page table in debugfs (diff) | |
| download | linux-dev-ab2cbeb0ed301a9f0460078e91b09f39958212ef.tar.xz linux-dev-ab2cbeb0ed301a9f0460078e91b09f39958212ef.zip | |
iommu/dma: Handle SG length overflow better
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>
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 6441197a75ea..4ea9cf02ba2d 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -762,7 +762,7 @@ 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 { |