Re: [PATCH] cpupower: Fix NULL pointer dereference on allocation failure

[Shuah Khan <skhan@linuxfoundation.org>]

On 7/4/26 02:43, Malaya Kumar Rout wrote:
> The bitmask_alloc() function can return NULL if memory allocation fails,
> but the code in main() does not check the return values before using the
> allocated bitmasks. This can lead to a NULL pointer dereference when
> bitmask_setall() or bitmask_parselist() is called with NULL pointers.
> 
> Add proper NULL checks after bitmask allocations and exit gracefully with
> an error message if allocation fails.
> 
> Fixes: 748f0d70087c ("cpupower: Provide online and offline CPU information")
> Signed-off-by: Malaya Kumar Rout <malayarout91@gmail.com>
> ---
>   tools/power/cpupower/utils/cpupower.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/tools/power/cpupower/utils/cpupower.c b/tools/power/cpupower/utils/cpupower.c
> index 9ec973165af1..8f7b18b8bb43 100644
> --- a/tools/power/cpupower/utils/cpupower.c
> +++ b/tools/power/cpupower/utils/cpupower.c
> @@ -184,6 +184,17 @@ int main(int argc, const char *argv[])
>   	online_cpus = bitmask_alloc(sysconf(_SC_NPROCESSORS_CONF));
>   	offline_cpus = bitmask_alloc(sysconf(_SC_NPROCESSORS_CONF));
>   
> +	if (!cpus_chosen || !online_cpus || !offline_cpus) {
> +		fprintf(stderr, _("Failed to allocate bitmasks\n"));
> +		if (cpus_chosen)
> +			bitmask_free(cpus_chosen);
> +		if (online_cpus)
> +			bitmask_free(online_cpus);
> +		if (offline_cpus)
> +			bitmask_free(offline_cpus);
> +		return EXIT_FAILURE;
> +	}
> +
>   	argc--;
>   	argv += 1;
>   

Usually these small allocations don't fail to warrant checks.

thanks,
-- Shuah