[PATCH] ptp: ocp: Add const to bp->attr_group allocation type

[PATCH] ptp: ocp: Add const to bp->attr_group allocation type

[Kees Cook]

In preparation for making the 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 returned
type, while technically matching, will be not const qualified. As there is
no general way to safely add const qualifiers, adjust the allocation type
to match the assignment.

Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: Jonathan Lemon <jonathan.lemon@gmail.com>
Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: <netdev@vger.kernel.org>
---
 drivers/ptp/ptp_ocp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index faf6e027f89a..ed5968a3ea5a 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -2372,7 +2372,7 @@ ptp_ocp_attr_group_add(struct ptp_ocp *bp,
 		if (attr_tbl[i].cap & bp->fw_cap)
 			count++;
 
-	bp->attr_group = kcalloc(count + 1, sizeof(struct attribute_group *),
+	bp->attr_group = kcalloc(count + 1, sizeof(*bp->attr_group),
 				 GFP_KERNEL);
 	if (!bp->attr_group)
 		return -ENOMEM;
-- 
2.34.1

Re: [PATCH] ptp: ocp: Add const to bp->attr_group allocation type

[Vadim Fedorenko]

On 26/04/2025 07:18, Kees Cook wrote:
> In preparation for making the 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 returned
> type, while technically matching, will be not const qualified. As there is
> no general way to safely add const qualifiers, adjust the allocation type
> to match the assignment.
> 
> Signed-off-by: Kees Cook <kees@kernel.org>
> ---
> Cc: Jonathan Lemon <jonathan.lemon@gmail.com>
> Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>
> Cc: Richard Cochran <richardcochran@gmail.com>
> Cc: Andrew Lunn <andrew+netdev@lunn.ch>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: <netdev@vger.kernel.org>
> ---
>   drivers/ptp/ptp_ocp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
> index faf6e027f89a..ed5968a3ea5a 100644
> --- a/drivers/ptp/ptp_ocp.c
> +++ b/drivers/ptp/ptp_ocp.c
> @@ -2372,7 +2372,7 @@ ptp_ocp_attr_group_add(struct ptp_ocp *bp,
>   		if (attr_tbl[i].cap & bp->fw_cap)
>   			count++;
>   
> -	bp->attr_group = kcalloc(count + 1, sizeof(struct attribute_group *),
> +	bp->attr_group = kcalloc(count + 1, sizeof(*bp->attr_group),
>   				 GFP_KERNEL);
>   	if (!bp->attr_group)
>   		return -ENOMEM;

Thanks,

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>

Re: [PATCH] ptp: ocp: Add const to bp->attr_group allocation type

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 25 Apr 2025 23:18:59 -0700 you wrote:
> In preparation for making the 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 returned
> type, while technically matching, will be not const qualified. As there is
> no general way to safely add const qualifiers, adjust the allocation type
> to match the assignment.
> 
> [...]

Here is the summary with links:
  - ptp: ocp: Add const to bp->attr_group allocation type
    https://git.kernel.org/netdev/net-next/c/5fe6530cd54b

You are awesome, thank you!
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