Re: [PATCH AUTOSEL 5.3 15/71] rbd: fix response length parameter for encoded strings

Ilya Dryomov
2019-10-01T17:15:54Z

On Tue, Oct 1, 2019 at 6:39 PM Sasha Levin <sashal@kernel.org> wrote:
>
> From: Dongsheng Yang <dongsheng.yang@easystack.cn>
>
> [ Upstream commit 5435d2069503e2aa89c34a94154f4f2fa4a0c9c4 ]
>
> rbd_dev_image_id() allocates space for length but passes a smaller
> value to rbd_obj_method_sync(). rbd_dev_v2_object_prefix() doesn't
> allocate space for length. Fix both to be consistent.
>
> Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
> Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/block/rbd.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index c8fb886aebd4e..69db7385c8df5 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -5669,17 +5669,20 @@ static int rbd_dev_v2_image_size(struct rbd_device *rbd_dev)
>
> static int rbd_dev_v2_object_prefix(struct rbd_device *rbd_dev)
> {
> + size_t size;
> void *reply_buf;
> int ret;
> void *p;
>
> - reply_buf = kzalloc(RBD_OBJ_PREFIX_LEN_MAX, GFP_KERNEL);
> + /* Response will be an encoded string, which includes a length */
> + size = sizeof(__le32) + RBD_OBJ_PREFIX_LEN_MAX;
> + reply_buf = kzalloc(size, GFP_KERNEL);
> if (!reply_buf)
> return -ENOMEM;
>
> ret = rbd_obj_method_sync(rbd_dev, &rbd_dev->header_oid,
> &rbd_dev->header_oloc, "get_object_prefix",
> - NULL, 0, reply_buf, RBD_OBJ_PREFIX_LEN_MAX);
> + NULL, 0, reply_buf, size);
> dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
> if (ret < 0)
> goto out;
> @@ -6696,7 +6699,6 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
> dout("rbd id object name is %s\n", oid.name);
>
> /* Response will be an encoded string, which includes a length */
> -
> size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX;
> response = kzalloc(size, GFP_NOIO);
> if (!response) {
> @@ -6708,7 +6710,7 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
>
> ret = rbd_obj_method_sync(rbd_dev, &oid, &rbd_dev->header_oloc,
> "get_id", NULL, 0,
> - response, RBD_IMAGE_ID_LEN_MAX);
> + response, size);
> dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
> if (ret == -ENOENT) {
> image_id = kstrdup("", GFP_KERNEL);

Hi Sasha,

This patch just made things consistent, there was no bug here. I don't
think it should be backported.

Thanks,

Ilya