[PATCH] coresight: cti: Add const to con_groups allocation type

[PATCH] coresight: cti: Add const to con_groups allocation type

[Kees Cook]

From: Kees Cook <kees+treewide@kernel.org>

In preparation for making the devm_kmalloc family of allocators type
aware, we need to make sure that the returned type from the allocation
matches the type of the variable being assigned. (Before, the allocator
would always return "void *", which can be implicitly cast to any
pointer type.)

The assigned type is "const struct attribute_group **", but the
converted allocation type would be "struct attribute_group **", which is
the same type without the const qualifier. As there is no general way to
safely add const qualifiers, take the size from the assignment target
instead. No change in allocation size results.

Build tested ARCH=arm64 allmodconfig with GCC aarch64-linux-gnu 16.1.0:
drivers/hwtracing/coresight/coresight-cti-sysfs.o

Assisted-by: LLM coccinelle
Signed-off-by: Kees Cook <kees+treewide@kernel.org>
---
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@arm.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: <coresight@lists.linaro.org>
Cc: <linux-arm-kernel@lists.infradead.org>
---
 drivers/hwtracing/coresight/coresight-cti-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
index 3fe2c916d228..2ed5d8eb1dda 100644
--- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
@@ -1132,7 +1132,7 @@ static int cti_create_cons_groups(struct device *dev, struct cti_device *ctidev)
 	/* nr groups = dynamic + static + NULL terminator */
 	nr_groups = ctidev->nr_trig_con + CORESIGHT_CTI_STATIC_GROUPS_MAX;
 	ctidev->con_groups = devm_kcalloc(dev, nr_groups,
-					  sizeof(struct attribute_group *),
+					  sizeof(*ctidev->con_groups),
 					  GFP_KERNEL);
 	if (!ctidev->con_groups)
 		return -ENOMEM;
-- 
2.34.1

Re: [PATCH] coresight: cti: Add const to con_groups allocation type

[Mike Leach]

Reviewed-by: Mike Leach <mike.leach@arm.com>


On 9/17/26 22:14, Kees Cook wrote:
> From: Kees Cook <kees+treewide@kernel.org>
> 
> In preparation for making the devm_kmalloc family of allocators type
> aware, we need to make sure that the returned type from the allocation
> matches the type of the variable being assigned. (Before, the allocator
> would always return "void *", which can be implicitly cast to any
> pointer type.)
> 
> The assigned type is "const struct attribute_group **", but the
> converted allocation type would be "struct attribute_group **", which is
> the same type without the const qualifier. As there is no general way to
> safely add const qualifiers, take the size from the assignment target
> instead. No change in allocation size results.
> 
> Build tested ARCH=arm64 allmodconfig with GCC aarch64-linux-gnu 16.1.0:
> drivers/hwtracing/coresight/coresight-cti-sysfs.o
> 
> Assisted-by: LLM coccinelle
> Signed-off-by: Kees Cook <kees+treewide@kernel.org>
> ---
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Mike Leach <mike.leach@arm.com>
> Cc: James Clark <james.clark@linaro.org>
> Cc: Leo Yan <leo.yan@arm.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: <coresight@lists.linaro.org>
> Cc: <linux-arm-kernel@lists.infradead.org>
> ---
>   drivers/hwtracing/coresight/coresight-cti-sysfs.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> index 3fe2c916d228..2ed5d8eb1dda 100644
> --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> @@ -1132,7 +1132,7 @@ static int cti_create_cons_groups(struct device *dev, struct cti_device *ctidev)
>   	/* nr groups = dynamic + static + NULL terminator */
>   	nr_groups = ctidev->nr_trig_con + CORESIGHT_CTI_STATIC_GROUPS_MAX;
>   	ctidev->con_groups = devm_kcalloc(dev, nr_groups,
> -					  sizeof(struct attribute_group *),
> +					  sizeof(*ctidev->con_groups),
>   					  GFP_KERNEL);
>   	if (!ctidev->con_groups)
>   		return -ENOMEM;