linux-kernel - [PATCH] drm/bridge: adv7511: fix crash on irq during probe

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Message-Id: <20231014-adv7511-cec-irq-crash-fix-v1-1-3389486c8373@bang-olufsen.dk>
Date:   Sat, 14 Oct 2023 20:46:12 +0200
From:   Alvin Šipraga <alvin@...s.dk>
To:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Archit Taneja <architt@...eaurora.org>,
        Hans Verkuil <hans.verkuil@...co.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Mads Bligaard Nielsen <bli@...g-olufsen.dk>,
        Alvin Šipraga <alsi@...g-olufsen.dk>
Subject: [PATCH] drm/bridge: adv7511: fix crash on irq during probe

From: Mads Bligaard Nielsen <bli@...g-olufsen.dk>

Moved IRQ registration down to end of adv7511_probe().

If an IRQ already is pending during adv7511_probe
(before adv7511_cec_init) then cec_received_msg_ts
could crash using uninitialized data:

    Unable to handle kernel read from unreadable memory at virtual address 00000000000003d5
    Internal error: Oops: 96000004 [#1] PREEMPT_RT SMP
    Call trace:
     cec_received_msg_ts+0x48/0x990 [cec]
     adv7511_cec_irq_process+0x1cc/0x308 [adv7511]
     adv7511_irq_process+0xd8/0x120 [adv7511]
     adv7511_irq_handler+0x1c/0x30 [adv7511]
     irq_thread_fn+0x30/0xa0
     irq_thread+0x14c/0x238
     kthread+0x190/0x1a8

Fixes: 3b1b975003e4 ("drm: adv7511/33: add HDMI CEC support")
Signed-off-by: Mads Bligaard Nielsen <bli@...g-olufsen.dk>
Signed-off-by: Alvin Šipraga <alsi@...g-olufsen.dk>
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index d518de88b5c3..71022cb8abe4 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1291,17 +1291,6 @@ static int adv7511_probe(struct i2c_client *i2c)
 
 	INIT_WORK(&adv7511->hpd_work, adv7511_hpd_work);
 
-	if (i2c->irq) {
-		init_waitqueue_head(&adv7511->wq);
-
-		ret = devm_request_threaded_irq(dev, i2c->irq, NULL,
-						adv7511_irq_handler,
-						IRQF_ONESHOT, dev_name(dev),
-						adv7511);
-		if (ret)
-			goto err_unregister_cec;
-	}
-
 	adv7511_power_off(adv7511);
 
 	i2c_set_clientdata(i2c, adv7511);
@@ -1325,6 +1314,17 @@ static int adv7511_probe(struct i2c_client *i2c)
 
 	adv7511_audio_init(dev, adv7511);
 
+	if (i2c->irq) {
+		init_waitqueue_head(&adv7511->wq);
+
+		ret = devm_request_threaded_irq(dev, i2c->irq, NULL,
+						adv7511_irq_handler,
+						IRQF_ONESHOT, dev_name(dev),
+						adv7511);
+		if (ret)
+			goto err_unregister_audio;
+	}
+
 	if (adv7511->type == ADV7533 || adv7511->type == ADV7535) {
 		ret = adv7533_attach_dsi(adv7511);
 		if (ret)

---
base-commit: a48e2cc92835fa1d9b373b804b2173c779387b8e
change-id: 20231014-adv7511-cec-irq-crash-fix-6fdd9093dc7a