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 4F4CD606A328 for ; Tue, 27 Oct 2026 08:14:17 +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=J/USOVMi Received: by kanga.kvack.org (Postfix) id D42286B060F; Tue, 27 Oct 2026 04:14:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D19FD6B0611; Tue, 27 Oct 2026 04:14:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C32FB6B0612; Tue, 27 Oct 2026 04:14:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 9C4FB6B060F for ; Tue, 27 Oct 2026 04:14:15 -0400 (EDT) Received: from smtpin03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 2C45840692 for ; Tue, 27 Oct 2026 08:14:15 +0000 (UTC) X-FDA: 85367693670.03.5DE9E4A Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf31.hostedemail.com (Postfix) with ESMTP id 3A2E120008 for ; Tue, 27 Oct 2026 08:14:14 +0000 (UTC) Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="J/USOVMi"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf31.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793088853; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=X817yPMZ1OWa0GxllLA7n65tTL4HKJjURd5YVC5upNo=; b=00jSb6YDorn4isx24DU4CO5Dl4iNEjyJaDCZA5yNK5RLZ72GeXW4gWHBQdMrJFftu6/tbr fp0oEA/Mx7sQY9kYBjD7gQmixYkkqpJGHyf1jTntVp2JnyaWW/TWvSbAnpUwT052k1x97b lVAyNqhUC/OguvknSXz+saQ+RI1GC+I= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="J/USOVMi"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf31.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793088853; b=vnO6ldYCoatLciBSPcGeUKqPSJvW3bDXRcsOCxa0Jiyhdb/Y88OuRoTv8i1m4dfUrtrXsT i/d+dOjAao79GGlUNpJfMvdGNMNdcBpBDMpUYL5gkcybzu3ZrbF3gFpgKTATnIc14xbdt6 2MPOQjV2kMzn6rJmNfoCfrqLnPFdGzs= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id B2DA6421F3; Tue, 27 Oct 2026 08:14:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 252CE1F01825; Tue, 27 Oct 2026 08:13:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793088852; bh=X817yPMZ1OWa0GxllLA7n65tTL4HKJjURd5YVC5upNo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=J/USOVMiZdHACMBPrC+zND6awTBbtGUCKpChcm6jDubxlHzRsgGJJ33u8eAyXrHmm Dhgy64k1zoGSzetJ6uUKZtYgTjriJplQrDD5QgepgCioCGZAn0H/62PsYvRrAHq7MD l6KQxPT3ek/jTP3ay9yQuCHmqyJ6vEXgWsvrHA/OVEIl8w0qY2qNXPJSzKqR527RVT FfER0j6vK3yc1dfQ0wPeN924r3/nVS5+UFCB/hPBBJU9NfLcCTsCBk+HMbQu7cKkEk Dk6dNn7PD/Yz5EgpKrvi4Sup3qa7fOHH3IAb+PJBxHnNh8DjdBkIMjNxtAjcJHzrHd rlwjmVWf2kcCQ== Date: Tue, 27 Oct 2026 10:13:48 +0200 From: Mike Rapoport To: "David Hildenbrand (Arm)" 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 Subject: Re: [PATCH 03/46] mm/memfd: check for real shmem inodes before accessing shmem state Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-3-6f74bec9a5bb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-3-6f74bec9a5bb@kernel.org> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 3A2E120008 X-Stat-Signature: 91jrut3ii3babh5yg6g11ajomfri9b4j X-Spam-Status: No, score=-16.1 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 autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793088854-533686 X-HE-Meta: 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 81go/Lvd 2NA/FnWaclMBh2UOfBS9ddN1LtjCnZ6RCA/VPEy5y/01yKfqDCImC0YB0QNei14CWtRDLokOHPej3AArpsCvifEy5cMo1tzsc8QsbO+2jjWRwE5zl7uJbVGDJV0e3NqmS2BMYyaAFVvbO5fG8SO+lM+auEiSqI10ZCv2nUino8w/hJqtLdhV1zKlAIVRIRHeXFMmcNJUsCqIAk/PeBYHEgTJb/nYTc+dTO7srXZ/znx3hJO/Yup6l6IXqrBFDL1Cx3WKh22hjf05yqGHIq86QSdv9/ebBcvcqDV0DWCyNJP7enDOqMsSqMJrq77lkLMgxeRmDMPbLPxOpMzbspcmX0ztqWXisruvhv0qB 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 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? > bool shmem_mapping(const struct address_space *mapping); -- Sincerely yours, Mike.