From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793122465; b=siTa6Mqy5Juo7nlY4ynOYFtgkOUdY6zt2MalFSPDYAoO6uxy2TQbstPsMMsL2Fr+Us9Z NhZ2g9Xos2McqIZAz+AKKqR/FyeamMLKR9P3tA8pLAZYI/xnrgOfxskG7c5Oy03HmEoYD zbnb0uVzIUvwhzyPUv1kJMxB+54nsxMdzmSM8SBsHW+2yG1n6azBoZtgsHU9BxS2eFQOQ d5MT/X+D+bxj6oyptw8jXFbpQXnXy3qLPEtqum5GsFF3/klREy7JJSmyn1Dhm7y3OFuAZ Z3Ez4YM59AJpoGRmWL43glIKP9Oh6xwJcqqrw8bTbUydkR8M9fCuVOB93YuVMj2N6rg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793122465; h=Received:DKIM-Signature:From:To:Cc:Subject:In-Reply-To:References: Date:Message-ID:User-Agent:MIME-Version:Content-Type; bh=COdQsqilLLQbumWXSPatN4LDhJMWTfOp2W8kqhDBWxs=; b=K5yotWVMsn7QNQBSi7Nt5tQjlqVBUlXBQw59gZb9rhnfMAqcaB8NRhgWJ5x/THRJnBpO Vh8Kl2Fy25i6tBL/NtqfAXwapRzwpJy+M7JijboTyHrGYsYLsutWUzBP8shTop9UDLXHs TS3rySUNyaNpoI7XiwmLC+UjAgnNY1rZoLzIT7MRjQm/GA2t6MTMpW1e4ZAoBQFDnjAF7 0YDbZ1xvMGyZKmkq/NB8QB8kIOa6crMVbVIiaWUV4Kdf2p6wSMc4IhMlOOpceTKocffr4 /NpWGHlXeOU0A6SZFHTtlEvJReHWV8fnvryfTXQhDrJIbL5p4Uyb/u8tobWTt+ozf5A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=RYN2vzKs; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B895606A31A; Tue, 27 Oct 2026 17:34:25 +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=RYN2vzKs Received: by smtp.kernel.org (Postfix) with ESMTPSA id E30B81F01825; Tue, 27 Oct 2026 17:34:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793122465; bh=COdQsqilLLQbumWXSPatN4LDhJMWTfOp2W8kqhDBWxs=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=RYN2vzKs4ZkzsggRNOd5345Y9RmP5xJuwIVm9w6r5x3FAJg1HBumtJ7kzq7Zk2Byv NJLY3MTki5J/jgMKffKX0MJUDmrh7Mj9/0LUeDWRGFT9PKDun2MDUk4bswpvOBod5/ bNYMieVVAxa9BIH2qgUZj85frA0Pfn970M2GP/0jc91EGPQZNOIAGmiPNiger8wclo ufyI4lp/osGtIkHDTUYogUM4fs20J692aYPNRbVq5x2xvqh4gPgqRcUB13BB9b5qSK oNjI1xXwG20lYigNS/pYDFW4KUWITLyuatPQ7hVvva5pYJEnM36h88Ce4pzq4aw8J6 m+957JU9t5eOA== From: Pratyush Yadav To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Gregory Price , Zi Yan , Joshua Hahn , Rakie Kim , Ying Huang , Johannes Weiner , Vladimir Davydov , Michal Hocko , Hugh Dickins , Baolin Wang , Lukas Czerner , Carlos Maiolino , Christian Brauner , Jan Kara , Daniel Verkamp , Jeff Xu , Muchun Song , Oscar Salvador , David Stevens , "Matthew Wilcox (Oracle)" , William Kucharski , Chris Li , Kairui Song , Nhat Pham , Miaohe Lin , Naoya Horiguchi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chris Mason , stable@vger.kernel.org, Pedro Falcato , "Kiryl Shutsemau (Meta)" Subject: Re: [PATCH v2 04/14] mm/shmem: honour F_SEAL_EXEC when an ACL is set In-Reply-To: <20261027-fixes_shmem-v2-4-86a00952acb9@kernel.org> (David Hildenbrand's message of "Tue, 27 Oct 2026 14:03:09 +0100") References: <20261027-fixes_shmem-v2-0-86a00952acb9@kernel.org> <20261027-fixes_shmem-v2-4-86a00952acb9@kernel.org> Date: Tue, 27 Oct 2026 18:34:18 +0100 Message-ID: <2vxz7bj3oxnp.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain On Tue, Oct 27 2026, David Hildenbrand (Arm) wrote: > From: Chris Mason > > The owner of a memfd sealed with F_SEAL_EXEC can still change its > execute bits by setting a POSIX access ACL. With CONFIG_TMPFS_POSIX_ACL, > this lets an unprivileged owner make a non-executable memfd executable, > bypassing vm.memfd_noexec=2. > > simple_set_acl() updates i_mode directly, bypassing the seal check in > shmem_setattr(). Add shmem_set_acl() to check the resulting mode. Share > the F_SEAL_EXEC check with shmem_setattr() using memfd_check_seals_mode() > in include/linux/memfd.h. > > Fix generated by an LLM and sent by Chris Mason in private. > > Fixes: 6fd7353829ca ("mm/memfd: add F_SEAL_EXEC") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > Acked-by: Pedro Falcato > Acked-by: Kiryl Shutsemau (Meta) > Acked-by: Zi Yan > Reviewed-by: Baolin Wang > Tested-by: Gregory Price (Meta) > [ david: use common helper; simplify description ] > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Pratyush Yadav (Google) [...] -- Regards, Pratyush Yadav