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

[Sasha Levin <sashal@xxxxxxxxxx>]

On Tue, Oct 01, 2019 at 07:15:49PM +0200, Ilya Dryomov wrote:
> On Tue, Oct 1, 2019 at 6:39 PM Sasha Levin <sashal@xxxxxxxxxx> wrote:
> > From: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
> >
> > [ 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@xxxxxxxxxxxx>
> > Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx>
> > Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >  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.

I'll drop it, thanks!

--
Thanks,
Sasha