* [PATCH] iommu: Fix offsetof() usage
@ 2019-04-08 12:41 Robin Murphy
2019-04-09 10:00 ` Christoph Hellwig
0 siblings, 1 reply; 2+ messages in thread
From: Robin Murphy @ 2019-04-08 12:41 UTC (permalink / raw)
To: joro; +Cc: iommu, David Laight, linux-arm-kernel
David rightly points out that, although GCC lets us get away with it,
using offsetof() with a non-constant member designator is not compliant
with the C standard. I'm responsible for a couple of those misuses, but
both in circumstances for which we now have a specific helper, so we can
use that to put things straight.
Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/iommu/arm-smmu.c | 3 +--
drivers/iommu/iommu.c | 2 +-
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 74e944bd4a8d..81d449451494 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1484,8 +1484,7 @@ static int arm_smmu_add_device(struct device *dev)
}
ret = -ENOMEM;
- cfg = kzalloc(offsetof(struct arm_smmu_master_cfg, smendx[i]),
- GFP_KERNEL);
+ cfg = kzalloc(struct_size(cfg, smendx, i), GFP_KERNEL);
if (!cfg)
goto out_free;
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 33a982e33716..ad28919e1452 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2021,7 +2021,7 @@ int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
if (!fwspec)
return -EINVAL;
- size = offsetof(struct iommu_fwspec, ids[fwspec->num_ids + num_ids]);
+ size = struct_size(fwspec, ids, fwspec->num_ids + num_ids);
if (size > sizeof(*fwspec)) {
fwspec = krealloc(fwspec, size, GFP_KERNEL);
if (!fwspec)
--
2.21.0.dirty
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] iommu: Fix offsetof() usage
2019-04-08 12:41 [PATCH] iommu: Fix offsetof() usage Robin Murphy
@ 2019-04-09 10:00 ` Christoph Hellwig
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2019-04-09 10:00 UTC (permalink / raw)
To: Robin Murphy; +Cc: joro, David Laight, iommu, linux-arm-kernel
> index 74e944bd4a8d..81d449451494 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1484,8 +1484,7 @@ static int arm_smmu_add_device(struct device *dev)
> }
>
> ret = -ENOMEM;
> - cfg = kzalloc(offsetof(struct arm_smmu_master_cfg, smendx[i]),
> - GFP_KERNEL);
> + cfg = kzalloc(struct_size(cfg, smendx, i), GFP_KERNEL);
This looks like a huge improvement, but I find the usage of i
here still very obsfucating. Can we please use fwspec->num_ids
directly instead of make it much more obvious?
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^ permalink raw reply [flat|nested] 2+ messages in thread
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