linux-kernel - [PATCH] sh: hp6xx: unset apm_get_power

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Message-ID: <ydtnrqqjuaz6uifqplujmqwdnpxoe7ma33d5hp4waavekerod2@tarta.nabijaczleweli.xyz>
Date: Fri, 17 Oct 2025 00:05:16 +0200
From: 
	Ahelenia Ziemiańska <nabijaczleweli@...ijaczleweli.xyz>
To: Yoshinori Sato <ysato@...rs.sourceforge.jp>, 
	Rich Felker <dalias@...c.org>, John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>, 
	Paul Mundt <lethal@...ux-sh.org>, Kristoffer Ericson <Kristoffer.Ericson@...il.com>, 
	linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] sh: hp6xx: unset apm_get_power_status on unload

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 <nabijaczleweli@...ijaczleweli.xyz>
---
 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);
 }
 
-- 
2.39.5

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