wt., 18 lut 2020 o 10:56 Srinivas Kandagatla
<srinivas.kandagatla@xxxxxxxxxx> napisał(a):
>
>
>
> On 18/02/2020 09:42, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> >
> > The nvmem struct is only freed on the first error check after its
> > allocation and leaked after that. Fix it with a new label.
> >
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> > ---
> > drivers/nvmem/core.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> > index b0be03d5f240..c9b3f4047154 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -343,10 +343,8 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> > return ERR_PTR(-ENOMEM);
> >
> > rval = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
> > - if (rval < 0) {
> > - kfree(nvmem);
> > - return ERR_PTR(rval);
> > - }
> > + if (rval < 0)
> > + goto err_free_nvmem;
> > if (config->wp_gpio)
> > nvmem->wp_gpio = config->wp_gpio;
> > else
> > @@ -432,6 +430,8 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> > put_device(&nvmem->dev);
> > err_ida_remove:
> > ida_simple_remove(&nvmem_ida, nvmem->id);
> > +err_free_nvmem:
> > + kfree(nvmem);
>
> This is not correct fix to start with, if the device has already been
> intialized before jumping here then nvmem would be freed as part of
> nvmem_release().
>
> So the bug was actually introduced by adding err_ida_remove label.
>
> You can free nvmem at that point but not at any point after that as
> device core would be holding a reference to it.
>
OK I see - I missed the release() callback assignment. Frankly: I find
this split of resource management responsibility confusing. Since the
users are expected to call nvmem_unregister() anyway - wouldn't it be
more clear to just free all resources there? What is the advantage of
defining the release() callback for device type here?
Bartosz
