summaryrefslogtreecommitdiffstats
path: root/drivers/iommu
diff options
context:
space:
mode:
authorRobin Murphy <robin.murphy@arm.com>2019-07-29 17:46:00 +0100
committerJoerg Roedel <jroedel@suse.de>2019-08-09 17:31:39 +0200
commitab2cbeb0ed301a9f0460078e91b09f39958212ef (patch)
treef63defbae2945d3846f20b852ccde41b9208f1b3 /drivers/iommu
parentbfeaec7f7d2f6b09764a1b48e88e9ca3d5076419 (diff)
downloadlinux-ab2cbeb0ed301a9f0460078e91b09f39958212ef.tar.gz
linux-ab2cbeb0ed301a9f0460078e91b09f39958212ef.tar.bz2
linux-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.c2
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 {