Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions).
While there, use struct_size() helper, instead of the open-coded version, to calculate the size for the allocation of the whole flexible structure, including of course, the flexible-array member. This code was found with the help of Coccinelle, and audited and fixed manually. Signed-off-by: Gustavo A. R. Silva <[email protected]> --- drivers/iommu/virtio-iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c index 17dcd826f5c2..379ebe03efb6 100644 --- a/drivers/iommu/virtio-iommu.c +++ b/drivers/iommu/virtio-iommu.c @@ -85,7 +85,7 @@ struct viommu_request { void *writeback; unsigned int write_offset; unsigned int len; - char buf[]; + char buf[] __counted_by(len); }; #define VIOMMU_FAULT_RESV_MASK 0xffffff00 @@ -230,7 +230,7 @@ static int __viommu_add_req(struct viommu_dev *viommu, void *buf, size_t len, if (write_offset <= 0) return -EINVAL; - req = kzalloc(sizeof(*req) + len, GFP_ATOMIC); + req = kzalloc(struct_size(req, buf, len), GFP_ATOMIC); if (!req) return -ENOMEM; -- 2.34.1
