linux-kernel - Re: [syzbot] [media?] KASAN: slab-use-after-free Read in media_devnode

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Message-ID: <tencent_D2897063A84456F7739765A6C3B375836505@qq.com>
Date: Wed, 10 Sep 2025 08:42:31 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+031d0cfd7c362817963f@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [media?] KASAN: slab-use-after-free Read in media_devnode_unregister

#syz test

diff --git a/drivers/media/mc/mc-devnode.c b/drivers/media/mc/mc-devnode.c
index 0d01cbae98f2..6daa7aa99442 100644
--- a/drivers/media/mc/mc-devnode.c
+++ b/drivers/media/mc/mc-devnode.c
@@ -276,13 +276,10 @@ void media_devnode_unregister(struct media_devnode *devnode)
 	/* Delete the cdev on this minor as well */
 	cdev_device_del(&devnode->cdev, &devnode->dev);
 	devnode->media_dev = NULL;
+	clear_bit(devnode->minor, media_devnode_nums);
 	mutex_unlock(&media_devnode_lock);
 
 	put_device(&devnode->dev);
-
-	mutex_lock(&media_devnode_lock);
-	clear_bit(devnode->minor, media_devnode_nums);
-	mutex_unlock(&media_devnode_lock);
 }
 
 /*