linux-kernel - [PATCH] proc: fix type confusion in pde_set

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Message-ID: <20250904135715.3972782-1-wangzijie1@honor.com>
Date: Thu, 4 Sep 2025 21:57:15 +0800
From: wangzijie <wangzijie1@...or.com>
To: <akpm@...ux-foundation.org>, <brauner@...nel.org>,
	<viro@...iv.linux.org.uk>, <adobriyan@...il.com>
CC: <jirislaby@...nel.org>, <sbrivio@...hat.com>,
	<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>, wangzijie
	<wangzijie1@...or.com>, Brad Spengler <spender@...ecurity.net>
Subject: [PATCH] proc: fix type confusion in pde_set_flags()

Commit 2ce3d282bd50 ("proc: fix missing pde_set_flags() for net proc files")
missed a key part in the definition of proc_dir_entry:

union {
	const struct proc_ops *proc_ops;
	const struct file_operations *proc_dir_ops;
};

So dereference of ->proc_ops assumes it is a proc_ops structure results in
type confusion and make NULL check for 'proc_ops' not work for proc dir.

Add !S_ISDIR(dp->mode) test before calling pde_set_flags() to fix it.

Fixes: 2ce3d282bd50 ("proc: fix missing pde_set_flags() for net proc files")
Reported-by: Brad Spengler <spender@...ecurity.net>
Signed-off-by: wangzijie <wangzijie1@...or.com>
---
 fs/proc/generic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index bd0c099cf..176281112 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -393,7 +393,8 @@ struct proc_dir_entry *proc_register(struct proc_dir_entry *dir,
 	if (proc_alloc_inum(&dp->low_ino))
 		goto out_free_entry;
 
-	pde_set_flags(dp);
+	if (!S_ISDIR(dp->mode))
+		pde_set_flags(dp);
 
 	write_lock(&proc_subdir_lock);
 	dp->parent = dir;
-- 
2.25.1