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b=MpJVcMTYApPZc7VozOSSmaXGxWwwgxOxiDGjTzhesY26ZSs/xNhwwdDIDL0zR46b0 W24cPjHL9Gyz2tmsdI2SZ1yAOIBcFIhBnPjCrQg2xaMcZtEWnbfvhWfVUXxY1N/Y+1 x7BIMwdp4kJhjoQq27aXY340AMvCIq9P2DrFIOyfPVCPJ5xs9RWXl9JHBQYKOWuud8 wvITPU/pQjvqn+W9V89fmzuCuW4Cwhv2tpUp3HqbUNBmkJwQ0riUqK0zrXSlsQ65ZJ l3Cj8QQbq5mCnD/EO8LJr58gJzqPZx/uTT9g4OZqsMUvqRomSCrCoZjw8Em01eokpW /XnZdvsBfixeQ== From: Christian Brauner Date: Sat, 14 Nov 2026 14:01:44 +0100 Subject: [PATCH RFC v2 03/42] target: fileio: check that the backing file supports ->{read,write}_iter X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261114-work-loop-pseudo-v2-3-98639a2286fb@kernel.org> References: <20261114-work-loop-pseudo-v2-0-98639a2286fb@kernel.org> In-Reply-To: <20261114-work-loop-pseudo-v2-0-98639a2286fb@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; 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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") Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig 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 ab9824a4852f1..a5391e57e9aa5 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