From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C92F9606A31C for ; Wed, 28 Oct 2026 23:14:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=l0vqsjTd; dkim=pass (2048-bit key, unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=KHEUPAxB DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=puyAoc6Jf4frehbhlLXQIfKglUE1ElIfqgej2JSgVAA=; b=l0vqsjTdiemE5PZOdYgHXYhOxl rhTS1TN73NaW/CxcAaE6vwsgSkG16acdzSxX6lxGKqAsBTDaf4ltge5tvDmGumiO1DmKoHf2j/DU0 xUEbaxf5Wi6qJaHdeKelm8hjkPb+F89wmy9k1ijGwYB7ukMGpudL+0l7931aB7VktoeBaGyEqizwk R+LkVMk+rdKCoFmA6+Ujl1pIkP2J5MRDdlSyOBWKuP3MJrt/+XYLeGJayn3zXNQCkmtvXD3NLmre8 K0dfk27GW/I79cDFz0QvxqQv15V7RwV9/MB7+FUsqBWoc2loDEg0++MD17f0hzZPOEe9v7uDJEOWM CIlRsQfQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMCqN-000000083Tq-1qFJ; Wed, 28 Oct 2026 23:14:07 +0000 Received: from mail-pf1-x434.google.com ([2607:f8b0:4864:20::434]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMCqL-000000083TW-0TOp for kexec@lists.infradead.org; Wed, 28 Oct 2026 23:14:06 +0000 Received: by mail-pf1-x434.google.com with SMTP id d2e1a72fcca58-8a60f90a924so697993b3a.3 for ; Wed, 28 Oct 2026 16:14:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1793229243; x=1793834043; darn=lists.infradead.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=puyAoc6Jf4frehbhlLXQIfKglUE1ElIfqgej2JSgVAA=; b=KHEUPAxBt2Du8BFnG9yArpgMF9/I74vIUHhowZJ1Lsh8jPgBgn51jGDGU35p3Jjuxh iwmCLwxvubx/zQELhGi04rGeHaNgO45MuMjiK0PTD8AuZWpCsdxzV/DDtARjTkB30p6c Vu7o5AM7SGbzVyLtIkVcpVfq06zAVoKV8PRR/e2paSsv14ncOcNTpJk0TFIaMxrkGS/9 lAnMiHvMfRBSgO4no/OTZvkPAcJ+nc3oR8dXJfQyQqX38ZRRsDHplkaYEedeMc+F5sRy IIS9Ry77Yf08D6JA2q2UeQqJtyqBgbxnSi/zFUysjFRrDfTHuCzK3aQfZmBubPf4zHTs V5lw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793229243; x=1793834043; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=puyAoc6Jf4frehbhlLXQIfKglUE1ElIfqgej2JSgVAA=; b=CFxcxZaFaJB0nvw+vXWWsP9TcRBXc1pRYZWqPrDLKb3mvVrWJ87HZnqP6gGPEwJ9jT eii8nrGTRdYLrKQihABa5dTJETXU2wO4CeHHYdkHN20kJJwMOIAVb8FxQiAo/Bw1JOf5 A8BMiTogjq9xb+f36uPSB6ngbTtF6cddbsnQGRAoitipGzcxxPgFeGwlDK0OZYqHfxw1 oOM4dlZA8PnV1OVyqDLGxJC2ns0nucWihMZdfZ1YF2G4ZLNuzjVZFccvu9KUeyluV/7d 9LMMkvpF5oTxQdYGpXQ7YBJF/811RVhN/MrQnRDJAS9bvuyDQPsTXIyNBa4iyYo4n9jF hddQ== X-Gm-Message-State: AFq9FYLrDjAaYWErp/Jxgj4xYXARqUVwWKxF18M3npk5ZowgDOYMhz3X n1F9RgIkxjBCfV6fcit1brcr3iccvLwmiaM4VnbdF3r1wbijGRuWbd03sG8ZQ5/zoQ== X-Gm-Gg: AYBFou1luCrLdVBj4oYuvLUgoFVdW6WOE4m1HMQPlxf9pi1RZRHm4EWJV8//c7C8Kol x+gItpK2AL7jhPv/IX6dJviGtR0YqUrE2S/Iy4s8HwFgAFI6Jy3cD340ClRkLBDV3ZB3ArUkEWc Jw6o5o7GkEPWwMdlOli4RtbIb6NL0dI74kbi9Mal7zZa9ja0xjjc5SuPk67HlPiXxAjhJ51A5Gs IFzYzDuepRPQrczpEGLsKR5zYTCWEHypyKVF1uvVAMqtKCKUEBMBv9PSIvMBrCAeaz6qN2Lh80P XUEZhrjCvC2MljPu7ksoFMdt5zP8721ZhaSH1ebhkIOCPTncnPPZsHNHJ/D/4qWm6EVnfiuAgQu O32T/EiA9qUuvNNP/9zVDARZTwDnVT69YIcIQ7UXkZIMke3TrmA1ZvD/rBXMDzgekLKu/yAVIgl 16N/HFXwv/zskXW4Fkx9VCymfEQqTBG6TLgWI13sEypvTTdTn/srhcCNhezeIkzlGDBejFX0dtd LOdu52AN+Fziof7ZoyS0a0CpRTLFIgyNgMOpXkjnpdSiCNui7XiXhQIrZMu8zkmtb/A6IHnql+9 YZU1q9ETKbYj3HqBDj90bf+XP9/5shkaMUo9ecbw8exny8dFmETkwbCoGVuX9kltJ8AlQK8oZEG iZBSedCdsanrIwZY/ X-Received: by 2002:a05:6a20:914c:b0:3d3:af85:eb98 with SMTP id adf61e73a8af0-3e9022d6cbemr3267144637.26.1793229242275; Wed, 28 Oct 2026 16:14:02 -0700 (PDT) Received: from google.com (192.150.203.35.bc.googleusercontent.com. [35.203.150.192]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8a6a6cfa342sm1626775b3a.41.2026.10.28.16.14.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Oct 2026 16:14:01 -0700 (PDT) Date: Wed, 28 Oct 2026 23:13:57 +0000 From: David Matlack To: sashiko-reviews@lists.linux.dev Cc: kexec@lists.infradead.org, linux-mm@kvack.org, Alexander Graf , Andrew Morton , Baolin Wang , Christian Brauner , David Hildenbrand , Hugh Dickins , Jonathan Corbet , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Randy Dunlap , Samiullah Khawaja , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka Subject: Re: [PATCH v2 09/10] mm/shmem_luo: Allow retrieving tmpfs files with O_RDONLY Message-ID: References: <20261022225035.377445-1-dmatlack@google.com> <20261022225035.377445-10-dmatlack@google.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261028_161405_155520_59614379 X-CRM114-Status: GOOD ( 13.52 ) X-Spam-Score: -17.6 (-----------------) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-13.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 2026-10-23 10:51 PM, sashiko-bot@kernel.org wrote: > > + ro_file = dentry_open(&file->f_path, flags, current_cred()); > > + fput(file); > > + return ro_file; > > } > > > > static int shmem_luo_retrieve(struct liveupdate_file_op_args *args) > > [Severity: Medium] > When userspace retrieves a tmpfs file via LIVEUPDATE_SESSION_RETRIEVE_FD with > O_RDONLY in arg->flags, does passing the raw flags variable to dentry_open() > in shmem_luo_create_tmpfs_file() in mm/shmem_luo.c bypass the flag > normalization performed by file_open_root() -> build_open_flags()? > > In fs/open.c, build_open_flags() strips O_CLOEXEC and ensures O_DSYNC is set > when __O_SYNC is present: > > u64 flags = how->flags; > u64 strip = O_CLOEXEC; > ... > flags &= ~strip; > ... > if (flags & __O_SYNC) > flags |= O_DSYNC; > > Because dentry_open() -> alloc_empty_file() -> init_file() initializes > ro_file->f_flags directly from the passed flags and do_dentry_open() only > clears: > > f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC | __O_REGULAR); > f->f_iocb_flags = iocb_flags(f); > > passing O_RDONLY | O_CLOEXEC in arg->flags leaves O_CLOEXEC in > ro_file->f_flags (visible via fcntl(fd, F_GETFL) and /proc//fdinfo/), > and passing O_RDONLY | __O_SYNC without O_DSYNC leaves O_DSYNC and IOCB_DSYNC > unset on ro_file. > > Should dentry_open() be passed (file->f_flags & ~O_ACCMODE) | O_RDONLY instead > of flags so that ro_file uses the normalized flags from file? Yes. I will fix this in v3 to re-open the read-only file with the flags that file_open_root() already normalized.