Re: [PATCH v2] arc: validate DT CPU map strings before parsing them

[Vineet Gupta <vgupta@kernel.org>]

On 4/6/26 00:00, Pengpeng Hou wrote:
> arc_get_cpu_map() fetches the possible-cpus or present-cpus property
> from the flat DT and immediately passes the raw pointer to
> cpulist_parse(). That parser expects a NUL-terminated text buffer, but
> this path does not prove that the DT property is terminated within its
> declared bounds.
>
> Reject unterminated CPU-map properties before handing them to
> cpulist_parse().
>
> Changes since v1:
> - fold the NUL-termination check into the initial lookup test, as
>    suggested by Vineet Gupta
>
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>

Acked-by: Vineet Gupta <vgupta@kernel.org>


I've queued it for next ARC pull request, after the rc1 since we are on 
the verge of merge window.


Thx,

-Vineet

> ---
>   arch/arc/kernel/smp.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
> index b2f2c59279a6..632976c22107 100644
> --- a/arch/arc/kernel/smp.c
> +++ b/arch/arc/kernel/smp.c
> @@ -22,6 +22,7 @@
>   #include <linux/irqdomain.h>
>   #include <linux/export.h>
>   #include <linux/of_fdt.h>
> +#include <linux/string.h>
>   
>   #include <asm/mach_desc.h>
>   #include <asm/setup.h>
> @@ -43,9 +44,10 @@ static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
>   {
>   	unsigned long dt_root = of_get_flat_dt_root();
>   	const char *buf;
> +	int len;
>   
> -	buf = of_get_flat_dt_prop(dt_root, name, NULL);
> -	if (!buf)
> +	buf = of_get_flat_dt_prop(dt_root, name, &len);
> +	if (!buf || !memchr(buf, '\0', len))
>   		return -EINVAL;
>   
>   	if (cpulist_parse(buf, cpumask))
>   		return -EINVAL;
>   
>   	return 0;
>   }

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