linux-kernel - Re: [syzbot] [usb?] memory leak in class

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Date:   Tue, 16 May 2023 15:54:46 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     syzbot <syzbot+e7afd76ad060fa0d2605@...kaller.appspotmail.com>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        rafael@...nel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [usb?] memory leak in class_create

On Mon, May 01, 2023 at 09:53:45AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    22b8cc3e78f5 Merge tag 'x86_mm_for_6.4' of git://git.kerne..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16fc7958280000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5046ebeca744dd40
> dashboard link: https://syzkaller.appspot.com/bug?extid=e7afd76ad060fa0d2605
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1599a2b4280000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14eb395fc80000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/3ad2088c196b/disk-22b8cc3e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/61919a5b89c6/vmlinux-22b8cc3e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/a7adb5503ac8/bzImage-22b8cc3e.xz

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 22b8cc3e78f5


diff --git a/drivers/base/class.c b/drivers/base/class.c
index ac1808d1a2e8..9b44edc8416f 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -320,6 +322,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
 		start_knode = &start->p->knode_class;
 	klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
 	iter->type = type;
+	iter->sp = sp;
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 
@@ -361,6 +364,7 @@ EXPORT_SYMBOL_GPL(class_dev_iter_next);
 void class_dev_iter_exit(struct class_dev_iter *iter)
 {
 	klist_iter_exit(&iter->ki);
+	subsys_put(iter->sp);
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 
diff --git a/include/linux/device/class.h b/include/linux/device/class.h
index 9deeaeb457bb..abf3d3bfb6fe 100644
--- a/include/linux/device/class.h
+++ b/include/linux/device/class.h
@@ -74,6 +74,7 @@ struct class {
 struct class_dev_iter {
 	struct klist_iter		ki;
 	const struct device_type	*type;
+	struct subsys_private		*sp;
 };
 
 int __must_check class_register(const struct class *class);