linux-kernel - Re: [syzbot] [kernel?] possible deadlock in binder_alloc_free

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Message-ID: <20250112014856.1791-1-hdanton@sina.com>
Date: Sun, 12 Jan 2025 09:48:55 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+799a2d4576c454ac2693@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [kernel?] possible deadlock in binder_alloc_free_page

On Sat, 11 Jan 2025 02:30:22 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    7b4b9bf203da Add linux-next specific files for 20250107
> git tree:       linux-next
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10302dc4580000

#syz test

--- x/drivers/android/binder_alloc.c
+++ y/drivers/android/binder_alloc.c
@@ -1245,10 +1245,12 @@ void binder_alloc_init(struct binder_all
 	INIT_LIST_HEAD(&alloc->buffers);
 }
 
+static struct lock_class_key key;
 int binder_alloc_shrinker_init(void)
 {
 	int ret;
 
+	binder_freelist.key = &key;
 	ret = list_lru_init(&binder_freelist);
 	if (ret)
 		return ret;
--- x/fs/debugfs/file.c
+++ y/fs/debugfs/file.c
@@ -87,9 +87,6 @@ static int __debugfs_file_get(struct den
 	if (!((unsigned long)d_fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)) {
 		fsd = d_fsd;
 	} else {
-		if (WARN_ON(mode == DBGFS_GET_ALREADY))
-			return -EINVAL;
-
 		fsd = kmalloc(sizeof(*fsd), GFP_KERNEL);
 		if (!fsd)
 			return -ENOMEM;
--