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Tue, 10 Nov 2026 09:16:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794302178; bh=Gz0dTGlDVhd9jZuYoUkGX2lhrZ2264KU/6i6/t2s/qo=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=acdAWRI/NWQPeclSOSX1wx7aC0LKlluyS9cBSHJE3wkVd14QHiIc1fpuayPl5zd9i 5PlhWZ8zSjOW5F7hXCq+D2EWuxi2Yrz1KJQlfH1Ws82ExeUkKbKfMFv5OMJs6qDQtI ivCs99Ag2xwlyttYhxW0mBoIpqSeDBKB/Xe0M7/566QfleEO1qmr3PSFpcBtLu8M6e 5uWOAFdagIG3gFGLfEvUEG0K5TUu2qe/wFq2GlzIwzmGbP9NF8Xz91S/ezjMWkYxIR Zb5P2oATbJq5OI9cQHCzsF+MUW36ITw3fxTIvJMhFJgrnQP7+jVDlJirwJqu0ZS1tv BoiZzSLVXO0sA== From: Christian Brauner Date: Tue, 10 Nov 2026 10:14:19 +0100 Subject: [PATCH RFC 03/41] target: fileio: check that the backing file supports ->{read,write}_iter X-Mailing-List: linux-erofs@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261110-work-loop-pseudo-v1-3-4c998976c6c7@kernel.org> References: <20261110-work-loop-pseudo-v1-0-4c998976c6c7@kernel.org> In-Reply-To: <20261110-work-loop-pseudo-v1-0-4c998976c6c7@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Jann Horn , Chris Mason , Josef Bacik , Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Alexander Viro , Jan Kara , linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, driver-core@lists.linux.dev, linux-mm@kvack.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, apparmor@lists.ubuntu.com, linux-nfs@vger.kernel.org, netdev@vger.kernel.org, fuse-devel@lists.linux.dev, linux-efi@vger.kernel.org, xen-devel@lists.xenproject.org, ocfs2-devel@lists.linux.dev, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-usb@vger.kernel.org, Amir Goldstein , linux-erofs@lists.ozlabs.org, linux-kselftest@vger.kernel.org, "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-ce4c1 X-Developer-Signature: v=1; a=openpgp-sha256; l=1375; i=brauner@kernel.org; h=from:subject:message-id; bh=g97QydFuuV3EqmGP6aEJJCN8xS9I93EqcEv7IXzLvEc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWR9ejDdONKlhY2V6c704xvOGr9csfDBT5O8DNkZzTyrW b98EX/9taOUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAi/p2MDOcnH/48I1xZ3H7D LsGX5rOm8IRo3DUzvJispdniOMP59DKGP3xBbsX6KZxq27yLJyS8Ft2xaLrf8V2fbigcXhGYuPX dSW4A X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Spam-Status: No, score=-18.8 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_GIT autolearn=unavailable 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 With fd_async_io=1 the fileio backend calls ->read_iter() and ->write_iter() of the backing file directly. The synchronous path goes through vfs_iter_read() and vfs_iter_write() which check for them but the aio path doesn't. So a backing file without them calls a NULL pointer on its first I/O. Refuse such files when configuring the device. On the synchronous path every read or write that needed the missing method failed with EINVAL anyway. Fixes: 769031c92c8b ("scsi: target: target/file: Add support of direct and async I/O") Signed-off-by: Christian Brauner (Amutable) --- drivers/target/target_core_file.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c index ab9824a4852f..a5391e57e9aa 100644 --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -144,6 +144,14 @@ static int fd_configure_device(struct se_device *dev) goto fail; } fd_dev->fd_file = file; + + if (!file->f_op->read_iter || !file->f_op->write_iter) { + pr_err("FILEIO: %s lacks ->read_iter or ->write_iter\n", + fd_dev->fd_dev_name); + ret = -EINVAL; + goto fail; + } + /* * If using a block backend with this struct file, we extract * fd_dev->fd_[block,dev]_size from struct block_device. -- 2.53.0