linux-kernel - [PATCH 5.15 209/530] drm: bridge: adv7511: unregister cec i2c device after cec adapter

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Message-Id: <20221024113054.536714973@linuxfoundation.org>
Date:   Mon, 24 Oct 2022 13:29:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        Robert Foss <robert.foss@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 209/530] drm: bridge: adv7511: unregister cec i2c device after cec adapter

From: Alvin Šipraga <alsi@...g-olufsen.dk>

[ Upstream commit 40cdb02cb9f965732eb543d47f15bef8d10f0f5f ]

cec_unregister_adapter() assumes that the underlying adapter ops are
callable. For example, if the CEC adapter currently has a valid physical
address, then the unregistration procedure will invalidate the physical
address by setting it to f.f.f.f. Whence the following kernel oops
observed after removing the adv7511 module:

    Unable to handle kernel execution of user memory at virtual address 0000000000000000
    Internal error: Oops: 86000004 [#1] PREEMPT_RT SMP
    Call trace:
     0x0
     adv7511_cec_adap_log_addr+0x1ac/0x1c8 [adv7511]
     cec_adap_unconfigure+0x44/0x90 [cec]
     __cec_s_phys_addr.part.0+0x68/0x230 [cec]
     __cec_s_phys_addr+0x40/0x50 [cec]
     cec_unregister_adapter+0xb4/0x118 [cec]
     adv7511_remove+0x60/0x90 [adv7511]
     i2c_device_remove+0x34/0xe0
     device_release_driver_internal+0x114/0x1f0
     driver_detach+0x54/0xe0
     bus_remove_driver+0x60/0xd8
     driver_unregister+0x34/0x60
     i2c_del_driver+0x2c/0x68
     adv7511_exit+0x1c/0x67c [adv7511]
     __arm64_sys_delete_module+0x154/0x288
     invoke_syscall+0x48/0x100
     el0_svc_common.constprop.0+0x48/0xe8
     do_el0_svc+0x28/0x88
     el0_svc+0x1c/0x50
     el0t_64_sync_handler+0xa8/0xb0
     el0t_64_sync+0x15c/0x160
    Code: bad PC value
    ---[ end trace 0000000000000000 ]---

Protect against this scenario by unregistering i2c_cec after
unregistering the CEC adapter. Duly disable the CEC clock afterwards
too.

Fixes: 3b1b975003e4 ("drm: adv7511/33: add HDMI CEC support")
Signed-off-by: Alvin Šipraga <alsi@...g-olufsen.dk>
Reviewed-by: Robert Foss <robert.foss@...aro.org>
Signed-off-by: Robert Foss <robert.foss@...aro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220612144854.2223873-3-alvin@pqrs.dk
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 7e3f6633f255..3dc551d223d6 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1326,8 +1326,6 @@ static int adv7511_remove(struct i2c_client *i2c)
 
 	if (adv7511->type == ADV7533 || adv7511->type == ADV7535)
 		adv7533_detach_dsi(adv7511);
-	i2c_unregister_device(adv7511->i2c_cec);
-	clk_disable_unprepare(adv7511->cec_clk);
 
 	adv7511_uninit_regulators(adv7511);
 
@@ -1336,6 +1334,8 @@ static int adv7511_remove(struct i2c_client *i2c)
 	adv7511_audio_exit(adv7511);
 
 	cec_unregister_adapter(adv7511->cec_adap);
+	i2c_unregister_device(adv7511->i2c_cec);
+	clk_disable_unprepare(adv7511->cec_clk);
 
 	i2c_unregister_device(adv7511->i2c_packet);
 	i2c_unregister_device(adv7511->i2c_edid);
-- 
2.35.1