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 9AF6F27A448; Mon, 18 Aug 2025 08:11:45 +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=1755504705; cv=none; b=q41ixDQuEiiYWEsHcIZWhoJqnl0iE3SGhYaZvglKK50FWgUt3fIZy3Bt8jVqfaVXsM+xYbBgmVSVS6gBjWKrywFLpCMmc7RKG4OI9mPHxbzSVNA2zFPjgOGdIdmAWXlRtRkKc78i1mH77iLmbNc97ERVlPEoePTbSkkZVHjYmMg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755504705; c=relaxed/simple; bh=DP1KwazJClhVRXDrH8PWSnWLV9BsJ0COvD3e1e112j8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WP3ykHzw7cCx1FVp4SaavzdsYiZXvzO4jpQNxMD70NIsWhugVxa/DkvlvsILnUv0YGk3U80ryUGq6/bX7TN3fbs6qZJk8fKTptTgydLz4SClsPnwz9ULPuHJCsgN2fMKsrf0Fqk7sVE3rymqFFps9iZwkcvYq1McUvE8vfnYT1Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sJMTFD2u; 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="sJMTFD2u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E73DAC4CEEB; Mon, 18 Aug 2025 08:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755504705; bh=DP1KwazJClhVRXDrH8PWSnWLV9BsJ0COvD3e1e112j8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=sJMTFD2uI0JkILTnes8k6jr6NjS/+jH9DNG+uSbV/PURDCsjvhBS2up6rStMzrYpg ROlxVInCCtaFEUp77ikP/xDRAa4ThG2Y0hlDxEqOED7f98taYVd3FLbnD0uUmwY0X+ reGOGTubd9nX+nAHaaleplrtKd1S23ZZNnG0fdMYebLWcNCRzLMHmYhQjfyTyS6zgI E2VDZyhCrrlm2ZDRtuM4uFeCNwXyKT01GPYKdsUErCtz66cW214dhLcl1HIeoZQKBI UaaLZOdiqgxsmcx3x3XSZEb8KqkyVz2c4IrFeAnW3NOzPkpc4nY8wCHO45bmJMNNMs GJNybeRqAIqug== Message-ID: <6b4debbf-028d-49e0-858f-dc72b37948c7@kernel.org> Date: Mon, 18 Aug 2025 10:11:41 +0200 Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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 Cc: adobriyan@gmail.com, akpm@linux-foundation.org, ast@kernel.org, gregkh@linuxfoundation.org, polynomial-c@gmx.de, regressions@lists.linux.dev, rick.p.edgecombe@intel.com, stable@vger.kernel.org, viro@zeniv.linux.org.uk, k.shutemov@gmail.com 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: 8bit k.shutemov no longer @ intel -> use gmail. On 18. 08. 25, 10:08, Jiri Slaby wrote: > 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) And to be honest, I would possibly move the 'if' into pde_set_flags(). >> +               pde_set_flags(dp); As here, it is not completely clear why you would want to test "dp->proc_ops" for something called "pde_set_flags". -- js suse labs