From 3abef3b3585bbc67d56fdc9c67761a900fb4b69d Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Mon, 13 May 2013 20:35:37 -0500 Subject: [PATCH] rbd: fix cleanup in rbd_add() Bjorn Helgaas pointed out that a recent commit introduced a use-after-free condition in an error path for rbd_add(). He correctly stated: I think b536f69a3a5 "rbd: set up devices only for mapped images" introduced a use-after-free error in rbd_add(): ... If rbd_dev_device_setup() returns an error, we call rbd_dev_image_release(), which ultimately kfrees rbd_dev. Then we call rbd_dev_destroy(), which references fields in the already-freed rbd_dev struct before kfreeing it again. The simple fix is to return the error code after the call to rbd_dev_image_release(). Closer examination revealed that there's no need to clean up rbd_opts in that function, so fix that too. Update some other comments that have also become out of date. Reported-by: Bjorn Helgaas Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 5f64ba77bc7f..3a897a531e9c 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -4700,8 +4700,10 @@ out: return ret; } -/* Undo whatever state changes are made by v1 or v2 image probe */ - +/* + * Undo whatever state changes are made by v1 or v2 header info + * call. + */ static void rbd_dev_unprobe(struct rbd_device *rbd_dev) { struct rbd_image_header *header; @@ -4905,9 +4907,10 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping) int tmp; /* - * Get the id from the image id object. If it's not a - * format 2 image, we'll get ENOENT back, and we'll assume - * it's a format 1 image. + * Get the id from the image id object. Unless there's an + * error, rbd_dev->spec->image_id will be filled in with + * a dynamically-allocated string, and rbd_dev->image_format + * will be set to either 1 or 2. */ ret = rbd_dev_image_id(rbd_dev); if (ret) @@ -5029,16 +5032,18 @@ static ssize_t rbd_add(struct bus_type *bus, rbd_dev->mapping.read_only = read_only; rc = rbd_dev_device_setup(rbd_dev); - if (!rc) - return count; + if (rc) { + rbd_dev_image_release(rbd_dev); + goto err_out_module; + } + + return count; - rbd_dev_image_release(rbd_dev); err_out_rbd_dev: rbd_dev_destroy(rbd_dev); err_out_client: rbd_put_client(rbdc); err_out_args: - kfree(rbd_opts); rbd_spec_put(spec); err_out_module: module_put(THIS_MODULE); -- 2.20.1