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

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Message-Id: <20250904155517.d623a254e8c25027c41e8e41@linux-foundation.org>
Date: Thu, 4 Sep 2025 15:55:17 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: wangzijie <wangzijie1@...or.com>
Cc: <brauner@...nel.org>, <viro@...iv.linux.org.uk>, <adobriyan@...il.com>,
 <jirislaby@...nel.org>, <sbrivio@...hat.com>,
 <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Brad
 Spengler <spender@...ecurity.net>
Subject: Re: [PATCH] proc: fix type confusion in pde_set_flags()

On Thu, 4 Sep 2025 21:57:15 +0800 wangzijie <wangzijie1@...or.com> wrote:

> 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")

2ce3d282bd50 had cc:stable, so I added cc:stable to this patch.

> Reported-by: Brad Spengler <spender@...ecurity.net>
> Signed-off-by: wangzijie <wangzijie1@...or.com>

A link to Brad's report would be helpful please, if available.  We
typically use Closes: for such things.