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 85E66606A32D for ; Wed, 4 Nov 2026 09:56:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=uUMXzD5u Received: by kanga.kvack.org (Postfix) id 9C4086B05B8; Wed, 4 Nov 2026 04:56:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 973A76B05B9; Wed, 4 Nov 2026 04:56:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 84FEF6B05BA; Wed, 4 Nov 2026 04:56:08 -0500 (EST) 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 64EC06B05B8 for ; Wed, 4 Nov 2026 04:56:08 -0500 (EST) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id E96C48066E for ; Wed, 4 Nov 2026 09:56:07 +0000 (UTC) X-FDA: 85396980774.15.8BD296C Received: from mta1.migadu.com (out-151.mta1.migadu.com [95.215.58.151]) by imf04.hostedemail.com (Postfix) with ESMTP id E40CB40003 for ; Wed, 4 Nov 2026 09:56:04 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=uUMXzD5u; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf04.hostedemail.com: domain of muchun.song@linux.dev designates 95.215.58.151 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793786166; 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=pUBQPp4DgGesu/zc45i1HHgbshamqgArN5rt8GOl5tk=; b=fKMK5RzGDJB7Y03Jg5IN+Q58HsmJPazPpcqVmNjUoFS5VbBKoSTT80pqCD0svpcmQI5LlE 5GKSaUKgontAkXsVwzRQvZKmMjK+1gUDxoVXZX8NhzKOpRC5cMYaQXI4VAiGE27s7Sx4Jx GWYwujJ3Gw9l0pYto39PubFgMeSEGKc= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=uUMXzD5u; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf04.hostedemail.com: domain of muchun.song@linux.dev designates 95.215.58.151 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793786166; b=678WbgyiMgsZjjdtQlzwS2S/McPV3pLHI5nZOOVhDKi8rLfgUJ0NjTK1qhMNjDNdcCyI// UsEUBPTt09+d6TYYdgFSvOGwT077UQwhruJVHrURiSo+V5ov3gsD6NJmMJP4m7h8V8DzKR FYVnU7pnvRJRe7sYn0Yg478SA6on+Iw= X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=pUBQPp4DgGesu/zc45i1HHgbshamqgArN5rt8GOl5tk=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793786163; v=1; x=1794390963; b=uUMXzD5u9LbfomWLcrC2JIgPQCBBTO3LbzHp+2JUyWLJ6xQdE2ZY1BMAOjdbQnBuSYP1qFjF 1kVjlex4v2hhEIm4aXGxezQoohio+Baq+fuznIdzLaWT6CPUvg34hb8PWHYCrHxsPlWU02MiA01 gVFlQhnLVU61YtHNeRs2gfcA= X-Envelope-To: linux-mm@kvack.org Received: by mta12.migadu.com with ESMTPS id c43ff3afd577f723; Wed, 04 Nov 2026 09:56:02 +0000 X-Mizu-Trace-ID: c43ff3afd577f723 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii X-Archived-By: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3901.200.71.1.16\)) Subject: Re: [PATCH 11/15] hugetlbfs: do not grow a sealed file in mmap() From: Muchun Song In-Reply-To: <20261028-fixes_hugetlb-v1-11-a0a033db180f@kernel.org> Date: Wed, 4 Nov 2026 17:55:32 +0800 Cc: Oscar Salvador , Naoya Horiguchi , Andrew Morton , Mel Gorman , Andy Whitcroft , Miaohe Lin , Michal Hocko , Rik van Riel , Hugh Dickins , Baolin Wang , Vivek Kasireddy , Dave Airlie , Jason Gunthorpe , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Jonathan Corbet , Shuah Khan , Randy Dunlap , Peter Xu , Breno Leitao , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Gerd Hoffmann , linux-doc@vger.kernel.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Chris Mason , stable@kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <140D6576-3DB1-464D-8934-6857B84EA784@linux.dev> References: <20261028-fixes_hugetlb-v1-0-a0a033db180f@kernel.org> <20261028-fixes_hugetlb-v1-11-a0a033db180f@kernel.org> To: "David Hildenbrand (Arm)" X-Mailer: Apple Mail (2.3901.200.71.1.16) X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E40CB40003 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: mcxzn55qtgqcg3zgffm369bywa51mdz4 X-HE-Tag: 1793786164-73019 X-HE-Meta: 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 zTWcQTbu dyLbjX1XMKN038AwF78R/ITHMrd1aanOgyhLR9QtIaO8+/9gZbM8gYO028AjJTDTUVVAUsq50oflDROEWjziEW8QiyqtTHaMoKLlcUHXXwByH8H1ON6fgK8doqjy84RziGG/s6IsDNgI9yiXGNogG5icqrx5qGd/2OAeslSxNLRqTUgKQTze49z0uaWz5VbM0lRM4KZxXt3UuGTWDsW3kmNq5u6q1ohAIZFUrAqKoFQQXNKNXFqHHkxlcjkbqGrRDV+4bo3qTSSILcXKWyhyWgcP0DUo+zkHUuQZaI1lG+CqdYE3Er8aPH7nK1M19/NBkOm/dekGHUpVD9sZEs2n8o5PyAo0OB1O1QdlZvox9LYRiRmTXvtJx/9ZqWGpDHF2j1LHieehU1Kgx0+3bNcyzM1qbzQ== 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 Oct 29, 2026, at 04:13, David Hildenbrand (Arm) = wrote: >=20 > From: Chris Mason >=20 > hugetlbfs_file_mmap() grows a file when a writable mapping extends = beyond > EOF. We are missing seal checks similar to hugetlbfs_setattr() and > hugetlbfs_fallocate(), allowing a user to grow a file that has = F_SEAL_GROW > set. >=20 > To fix it, skip the resize when F_SEAL_GROW is set; mmap() still = succeeds > without growing the file. >=20 > We currently also allow CoW mappings to grow a file. Disallowing this, > maybe even only for read-only file descriptors, could break existing > userspace, so we have to be more careful. QEMU's file backend is an > example user that might rely on such things, and would suddenly start > getting SIGBUS when faulting in memory outside EOF. >=20 > So be careful and focus on F_SEAL_GROW for now. >=20 > Fix generated by an LLM and sent by Chris Mason in private. >=20 > Fixes: ff62a3421044 ("hugetlb: implement memfd sealing") > Cc: stable@kernel.org > Signed-off-by: Chris Mason > [ david: drop comment; simplify+extend description ] > Signed-off-by: David Hildenbrand (Arm) Acked-by: Muchun Song Thanks.