This is a note to let you know that I've just added the patch titled nvmet: seset ns->file when open fails to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nvmet-seset-ns-file-when-open-fails.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d730761bc330615a29b5a4783521408cddc75b51 Author: Daniel Wagner <dwagner@xxxxxxx> Date: Wed May 12 16:50:05 2021 +0200 nvmet: seset ns->file when open fails [ Upstream commit 85428beac80dbcace5b146b218697c73e367dcf5 ] Reset the ns->file value to NULL also in the error case in nvmet_file_ns_enable(). The ns->file variable points either to file object or contains the error code after the filp_open() call. This can lead to following problem: When the user first setups an invalid file backend and tries to enable the ns, it will fail. Then the user switches over to a bdev backend and enables successfully the ns. The first received I/O will crash the system because the IO backend is chosen based on the ns->file value: static u16 nvmet_parse_io_cmd(struct nvmet_req *req) { [...] if (req->ns->file) return nvmet_file_parse_io_cmd(req); return nvmet_bdev_parse_io_cmd(req); } Reported-by: Enzo Matsumiya <ematsumiya@xxxxxxxx> Signed-off-by: Daniel Wagner <dwagner@xxxxxxx> Signed-off-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c index 05453f5d1448..6ca17a0babae 100644 --- a/drivers/nvme/target/io-cmd-file.c +++ b/drivers/nvme/target/io-cmd-file.c @@ -38,9 +38,11 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns) ns->file = filp_open(ns->device_path, flags, 0); if (IS_ERR(ns->file)) { - pr_err("failed to open file %s: (%ld)\n", - ns->device_path, PTR_ERR(ns->file)); - return PTR_ERR(ns->file); + ret = PTR_ERR(ns->file); + pr_err("failed to open file %s: (%d)\n", + ns->device_path, ret); + ns->file = NULL; + return ret; } ret = vfs_getattr(&ns->file->f_path,