From 8c82d6ec5abcf9691d37f329bf5f42f6868405db Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Mon, 7 Nov 2016 18:25:09 +0000 Subject: iommu/arm-smmu: Fix out-of-bounds dereference 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 Acked-by: Will Deacon Signed-off-by: Joerg Roedel --- drivers/iommu/arm-smmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/iommu') diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index d388629ab990..8f7281444551 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 fwspec_smendx(fw, i) \ + (i >= fw->num_ids ? INVALID_SMENDX : __fwspec_cfg(fw)->smendx[i]) #define for_each_cfg_sme(fw, i, idx) \ - for (i = 0; idx = __fwspec_cfg(fw)->smendx[i], i < fw->num_ids; ++i) + for (i = 0; idx = fwspec_smendx(fw, i), i < fw->num_ids; ++i) struct arm_smmu_device { struct device *dev; -- cgit v1.2.3