From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CE8B4606A31E for ; Tue, 27 Oct 2026 13:43:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=O/cT7rN4 Received: by kanga.kvack.org (Postfix) id D695B6B074D; Tue, 27 Oct 2026 09:43:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D41C66B074F; Tue, 27 Oct 2026 09:43:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C0A096B0750; Tue, 27 Oct 2026 09:43:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 9F9896B074D for ; Tue, 27 Oct 2026 09:43:01 -0400 (EDT) Received: from smtpin14.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 278EA809C8 for ; Tue, 27 Oct 2026 13:43:01 +0000 (UTC) X-FDA: 85368522162.14.25D6F41 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf09.hostedemail.com (Postfix) with ESMTP id 43EB614000D for ; Tue, 27 Oct 2026 13:42:59 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="O/cT7rN4"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf09.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793108579; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0+f6IJooHiQbF9wAyC4ax/+y1Gmk+/E4quNL5EJAkoQ=; b=UBfnmlDdRAyd/VHAIWuqYmb2dZjuCRghh6n0uXXwnWq1kbxDIqElsxEcwnM5rWNYcldzne VkWY1NGQkrDORa5VVgPRK0YxRRJDIJVQNTwIffRCwcVmMuKDvO546nWuoIIViy/yxTE7gD xCu9uFCxYzR+iAt36X5vdfTfIShk75Y= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="O/cT7rN4"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf09.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793108579; b=v0JC3B7rZKyLfGRFNxfJnv0aNCp20PRTtMSo2WNIfp72Ymfbyip/PjoSrQX+IzdnK4fUfs SkhGgN9K3FfeGptNe6y5bTIpGBZjViq2B5Dnbj5HXjCRIWCh82N3Mx9fBtPfFboCJR6jdb vAnquZ6b06jOB1CTj06Sx8ZYO1NufRU= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 5545643510; Tue, 27 Oct 2026 13:42:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 234691F01825; Tue, 27 Oct 2026 13:42:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793108578; bh=0+f6IJooHiQbF9wAyC4ax/+y1Gmk+/E4quNL5EJAkoQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=O/cT7rN4J4QJA9+qKjooI/EO5er0turCIeVkTDeBg9nmgtchbI+fpxO9S6+r+oBWY LwmatZaw1QbMHP8ScOJ6R+l2fGSrhmt7f6UUvC43uiHkIJGDGGCW0OQjZcEIUQEPa2 w142oOqbY6kYvnslUnzMN4PB88SswCTWpes66yGol6fQLmBbkQaxbQK69GdBHy5hRV glBMz2eRymovbjCzKL0DCgcuiVWEYF4wIngi0eCG9PplngO81D5jwjFqaadaqIhz3C 3l+I0Do+I4H43SEQfhyQdeFO3NHr7grqnLgvsjGY/hUxovAgKOJx9ptbOi6w43lJzE qaE/Jiu8PIH2w== Message-ID: <38491041-d167-4ea1-8813-e75bd11cd10f@kernel.org> Date: Tue, 27 Oct 2026 14:42:38 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 03/46] mm/memfd: check for real shmem inodes before accessing shmem state To: Mike Rapoport Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Chris Mason References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-3-6f74bec9a5bb@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 43EB614000D X-Rspam-User: X-Stat-Signature: ummpckmus8ajqm1i6q86efr5n134xkb3 X-Spam-Status: No, score=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam03 X-HE-Tag: 1793108579-310834 X-HE-Meta: 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 X2JTyT59 B17Ee/NKiYqc2SbmiJuCuAGxlsARmfUPrTrTxzR9lRBui72GEFlikzMx/xnhPSf1lLEhHN/lSnq1szpZdJ95KrX7WkkEB2rclsQITaYTMo3KROjBK2YlWYmjZXbjXP/VBM8mLtPk81MOGQ3G6ugI8t7S5WecfsxkTENTUl0YLFnzmua2Sd3BWt59VRnTCE/3sXSqtxIbu1dDyRBLL4vfl9xPOJnHe/PPpPFm4EzP4hABSnaoQyG6vhC0S9y+Yjn6iEIVx/apWiP4Pgj6TPYFzrRS1PeTZfSUcj8dp9gu/TbZM73k0zhN7XeAYwJ6JQXM91hzLQAqoFbibygpUlbG4u6jKxerswEWl0zJ2UE+bh3D9O2I= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/27/26 09:13, Mike Rapoport wrote: > On Tue, Oct 27, 2026 at 12:17:23AM +0100, David Hildenbrand (Arm) wrote: >> shmem_file() only checks a file's backing mapping. That mapping can belong >> to another file, as with a Coda file backed by a tmpfs container after >> mmap(). It does not establish that file_inode(file) is a shmem inode. >> >> Seal handling and memfd preservation use this check before accessing >> shmem inode state, so they can access an inode of the wrong type. >> >> Add file_inode_is_shmem() to check the inode's file operations in both >> paths. This identifies regular shmem inodes, including those used by >> memfds and ordinary tmpfs files, independently of wrapper file operations. >> >> Fixes: c49fcfcda8b5 ("mm/shmem: update file sealing comments and file checking") >> Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd") >> Cc: stable@vger.kernel.org >> Reported-by: Chris Mason >> Signed-off-by: David Hildenbrand (Arm) > > Reviewed-by: Mike Rapoport (Microsoft) > > With a small nit below > >> --- >> include/linux/shmem_fs.h | 6 ++++++ >> mm/memfd.c | 8 +++++--- >> mm/memfd_luo.c | 2 +- >> mm/shmem.c | 5 +++++ >> 4 files changed, 17 insertions(+), 4 deletions(-) >> >> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h >> index a7c7a96a7cbf9..2ceca7993e4f5 100644 >> --- a/include/linux/shmem_fs.h >> +++ b/include/linux/shmem_fs.h >> @@ -117,8 +117,14 @@ extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr, >> unsigned long len, unsigned long pgoff, unsigned long flags); >> extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts); >> #ifdef CONFIG_SHMEM >> +bool file_inode_is_shmem(const struct inode *inode); > > Do we really need the file_ prefix in this name? Good point, I intuitively added it. Can drop. Thanks! -- Cheers, David