From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C83F42F8BD1; Mon, 18 Aug 2025 08:08:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755504524; cv=none; b=HVRJF39S1axWc5uA4Oy0QLEE0Qk/t3cWEp6ZQ6VI/AJPf+ER0Mx5PWfoEFq6WhJNBF4FXdX5mRCWYBhegboKvwuEYsvEqEfv+pUCRm6ZWfEOT6n/dfX1VDF8y5sXTWTTrigILc899FxUb8g7/yY7dto9kV1Ip5hUWLN/a2mhDMs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755504524; c=relaxed/simple; bh=3gbMwLWpeu6BfJ+2J8ZRRqoihf6t7/L0bmG1IBQ4ZrM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cqB42bR2ugkAWog9NCPBAydxVU3/pHbzuo5U4igh1p4Lx1v+VUzufRMlfM+gXW+f0qp1IF0KR5Fj+7l+oWqiZRZQzfpgqEr14rPBoiXyJhgKcAYSq1tQAeexRgPixxOSk816C1mexj5HQGrXoyfb2XbHJBUQ5s3q9Y+WbRGlTlo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZuJu2Guw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZuJu2Guw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4420C116C6; Mon, 18 Aug 2025 08:08:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755504523; bh=3gbMwLWpeu6BfJ+2J8ZRRqoihf6t7/L0bmG1IBQ4ZrM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ZuJu2GuwEpqNR+e8nYaIPgor20+hVY7Hnhgmu+mawgs1vHbsrpa4hUDvnyS4lbDIf eQ6yDaxwA5hHw2qsq5p5vf/iJ3kbcBt4VQ/B0M3jxwZ3iO19/0wxa0fJvDYB2RQRlV qUxVT/GBhAKPjS7C3LkLhPwUSBcya/v1sp5afXhu3BMdYXcRQMtg5o2Wrz3U/BMVwm pS5707AzTtEgZLfAV01CsuYSgz6CuvzouIqn+484I95HLXbnw1K7YS68twbvfXMSiC CSNzATmUu3OxD2/vu+b+L2sIZLKrtiSv1pHN+VnBjNHmQBADfa4BotpG+bqgdoCoyC R9h6By5t78+gA== Message-ID: Date: Mon, 18 Aug 2025 10:08:38 +0200 Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] proc: fix wrong behavior of FMODE_LSEEK clearing for net related proc file To: wangzijie , jirislaby@kernel.org Cc: adobriyan@gmail.com, akpm@linux-foundation.org, ast@kernel.org, gregkh@linuxfoundation.org, kirill.shutemov@linux.intel.com, polynomial-c@gmx.de, regressions@lists.linux.dev, rick.p.edgecombe@intel.com, stable@vger.kernel.org, viro@zeniv.linux.org.uk References: <20250818080125.843285-1-wangzijie1@honor.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 18. 08. 25, 10:01, wangzijie wrote: >> Hi, >> >> On 18. 08. 25, 6:05, wangzijie wrote: >>> For avoiding pde->proc_ops->... dereference(which may cause UAF in rmmod race scene), >>> we call pde_set_flags() to save this kind of information in PDE itself before >>> proc_register() and call pde_has_proc_XXX() to replace pde->proc_ops->... dereference. >>> But there has omission of pde_set_flags() in net related proc file create, which cause >>> the wroing behavior of FMODE_LSEEK clearing in proc_reg_open() for net related proc file >>> after commit ff7ec8dc1b64("proc: use the same treatment to check proc_lseek as ones for >>> proc_read_iter et.al"). Lars reported it in this link[1]. So call pde_set_flags() when >>> create net related proc file to fix this bug. >> >> I wonder, why is pde_set_flags() not a part of proc_register()? > > Not all proc_dir_entry have proc_ops, so you mean this will be a better modification? > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > index 76e800e38..d52197c35 100644 > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -367,6 +367,20 @@ static const struct inode_operations proc_dir_inode_operations = { > .setattr = proc_notify_change, > }; > > +static void pde_set_flags(struct proc_dir_entry *pde) > +{ > + if (pde->proc_ops->proc_flags & PROC_ENTRY_PERMANENT) > + pde->flags |= PROC_ENTRY_PERMANENT; > + if (pde->proc_ops->proc_read_iter) > + pde->flags |= PROC_ENTRY_proc_read_iter; > +#ifdef CONFIG_COMPAT > + if (pde->proc_ops->proc_compat_ioctl) > + pde->flags |= PROC_ENTRY_proc_compat_ioctl; > +#endif > + if (pde->proc_ops->proc_lseek) > + pde->flags |= PROC_ENTRY_proc_lseek; > +} > + > /* returns the registered entry, or frees dp and returns NULL on failure */ > struct proc_dir_entry *proc_register(struct proc_dir_entry *dir, > struct proc_dir_entry *dp) > @@ -374,6 +388,9 @@ struct proc_dir_entry *proc_register(struct proc_dir_entry *dir, > if (proc_alloc_inum(&dp->low_ino)) > goto out_free_entry; > > + if (dp->proc_ops) > + pde_set_flags(dp); This occurs much saner and better to me. But I am no FS fellow. It's up to them to tell if it is the right thing to do. (The above hunks are missing removal of pde_set_flags() from the original location and removal of now unnecessary calls of pde_set_flags(). But I assume you would do that in a real/submitted patch.) thanks, -- js suse labs