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Haris Iqbal" , Jack Wang , Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Shuangpeng Bai , stable@vger.kernel.org Subject: [PATCH] rnbd-clt: fix use-after-free on device sysfs creation failure Date: Sat, 1 Aug 2026 23:13:50 -0400 Message-ID: <20260802031350.1468599-1-shuangpeng.kernel@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rnbd_clt_add_dev_kobj() initializes dev->kobj and adds it below the gendisk kobject after rnbd_clt_map_device() has returned a live rnbd_clt_dev to rnbd_clt_map_device_store(). If kobject_init_and_add() fails, the helper currently calls kobject_put() on the embedded kobject. That put can drop the initial kobject reference and run rnbd_dev_release(), freeing dev. The caller then continues through the normal error path and calls rnbd_clt_unmap_device(dev, true, NULL), dereferencing the freed device. Leave the initialized kobject alive until the normal device teardown has completed and rnbd_clt_put_dev() drops the final device reference. Since kobject_init_and_add() failure can leave the kobject initialized but not present in sysfs, only call kobject_del() from rnbd_destroy_sysfs() when state_in_sysfs is set. Fixes: 581cf833cac4 ("block: rnbd: add .release to rnbd_dev_ktype") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai --- drivers/block/rnbd/rnbd-clt-sysfs.c | 2 +- drivers/block/rnbd/rnbd-clt.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c index eb485e4c12e2..9f5d30659f3d 100644 --- a/drivers/block/rnbd/rnbd-clt-sysfs.c +++ b/drivers/block/rnbd/rnbd-clt-sysfs.c @@ -498,7 +498,7 @@ static int rnbd_clt_add_dev_kobj(struct rnbd_clt_dev *dev) if (ret) { rnbd_clt_err(dev, "Failed to create device sysfs dir, err: %d\n", ret); - kobject_put(&dev->kobj); + return ret; } kobject_uevent(gd_kobj, KOBJ_ONLINE); diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c index 4d6725a0035e..5fe5c7e259b7 100644 --- a/drivers/block/rnbd/rnbd-clt.c +++ b/drivers/block/rnbd/rnbd-clt.c @@ -1658,7 +1658,7 @@ static void rnbd_destroy_sysfs(struct rnbd_clt_dev *dev, const struct attribute *sysfs_self) { rnbd_clt_remove_dev_symlink(dev); - if (dev->kobj.state_initialized) { + if (dev->kobj.state_in_sysfs) { if (sysfs_self) /* To avoid deadlock firstly remove itself */ sysfs_remove_file_self(&dev->kobj, sysfs_self); -- 2.43.0