From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Mon, 7 Nov 2016 15:39:02 +0000 Subject: [PATCH] iommu/arm-smmu: Fix out-of-bounds dereference Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org When we iterate a master's config entries, what we generally care about is the entry's stream map index, rather than the entry index itself, so it's nice to have the iterator automatically assign the former from the latter. Unfortunately, booting with KASAN reveals the oversight that using a simple comma operator results in the entry index being dereferenced before being checked for validity, so we always access one element past the end of the fwspec array. Flip things around so that the check always happens before the index may be dereferenced. Fixes: adfec2e709d2 ("iommu/arm-smmu: Convert to iommu_fwspec") Reported-by: Mark Rutland Signed-off-by: Robin Murphy --- drivers/iommu/arm-smmu.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index f86683eec446..44ffe3a391d6 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -324,8 +324,10 @@ struct arm_smmu_master_cfg { #define INVALID_SMENDX -1 #define __fwspec_cfg(fw) ((struct arm_smmu_master_cfg *)fw->iommu_priv) #define fwspec_smmu(fw) (__fwspec_cfg(fw)->smmu) -#define for_each_cfg_sme(fw, i, idx) \ - for (i = 0; idx = __fwspec_cfg(fw)->smendx[i], i < fw->num_ids; ++i) +#define for_each_cfg_sme(fw, i, idx) \ + for (i = 0; \ + i < fw->num_ids && (idx = __fwspec_cfg(fw)->smendx[i], true); \ + ++i) struct arm_smmu_device { struct device *dev; -- 2.10.2.dirty