Re: [PATCH] sh: hp6xx: unset apm_get_power_status on unload

Hi Ahelenia,

On Fri, 2025-10-17 at 00:05 +0200, Ahelenia Ziemiańska wrote:
> The API for apm_get_power_status is "call it if it isn't NULL".
> If the module is unloaded and it's not unset,
> reading /proc/apm will jump into unloaded kernel memory.
> 
> The first commit that added this incompletely refactored
> the assigned-to variable in __exit,
> the second deleted it instead of fixing it.
> 
> Unset it on unload like drivers/macintosh/apm_emu.c.
> 
> Fixes: 0a9b0db19262 ("[APM] SH: Convert to use shared APM emulation.")
> Fixes: 8c8ee8254767 ("sh: hp6xx: APM build fix and new battery values.")
> Signed-off-by: Ahelenia Ziemiańska <[email protected]>
> ---
>  arch/sh/boards/mach-hp6xx/hp6xx_apm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/sh/boards/mach-hp6xx/hp6xx_apm.c b/arch/sh/boards/mach-hp6xx/hp6xx_apm.c
> index e5c4c7d34139..089eca39c4e6 100644
> --- a/arch/sh/boards/mach-hp6xx/hp6xx_apm.c
> +++ b/arch/sh/boards/mach-hp6xx/hp6xx_apm.c
> @@ -98,6 +98,9 @@ static int __init hp6x0_apm_init(void)
>  
>  static void __exit hp6x0_apm_exit(void)
>  {
> +	if (apm_get_power_status == hp6x0_apm_get_power_status)
> +		apm_get_power_status = NULL;
> +
>  	free_irq(HP680_BTN_IRQ, 0);
>  }
>  

Let's CC Artur Rojek who has worked on the hp6xx code before and should give his ACK.

Adrian

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