2019-03-25 21:57:50

by Aditya Pakki

Subject: [PATCH v4] nvdimm: btt_devs: fix a NULL pointer dereference

In case kmemdup fails, the fix releases resources and returns to
avoid the NULL pointer dereference.

Signed-off-by: Aditya Pakki <[email protected]>

---
v3: Move kfree(nd_btt) to goto block.
v2: Replace incorrect kfree with ida_simple_remove, suggested by
Johannes Thumshirn
v1: Free nd_btt->id in case of failure and avoid double free, suggested
by Dan Williams
---
drivers/nvdimm/btt_devs.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index b72a303176c7..9486acc08402 100644
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -198,14 +198,15 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
return NULL;

nd_btt->id = ida_simple_get(&nd_region->btt_ida, 0, 0, GFP_KERNEL);
- if (nd_btt->id < 0) {
- kfree(nd_btt);
- return NULL;
- }
+ if (nd_btt->id < 0)
+ goto out_nd_btt;

nd_btt->lbasize = lbasize;
- if (uuid)
+ if (uuid) {
uuid = kmemdup(uuid, 16, GFP_KERNEL);
+ if (!uuid)
+ goto out_put_id;
+ }
nd_btt->uuid = uuid;
dev = &nd_btt->dev;
dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
@@ -220,6 +221,13 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
return NULL;
}
return dev;
+
+out_put_id:
+ ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
+
+out_nd_btt:
+ kfree(nd_btt);
+ return NULL;
}

struct device *nd_btt_create(struct nd_region *nd_region)
--
2.17.1

2019-03-26 10:24:28

by Mukesh Ojha

Subject: Re: [PATCH v4] nvdimm: btt_devs: fix a NULL pointer dereference

On 3/26/2019 3:25 AM, Aditya Pakki wrote:
> In case kmemdup fails, the fix releases resources and returns to
> avoid the NULL pointer dereference.
>
> Signed-off-by: Aditya Pakki <[email protected]>
>
> ---
> v3: Move kfree(nd_btt) to goto block.
> v2: Replace incorrect kfree with ida_simple_remove, suggested by
> Johannes Thumshirn
> v1: Free nd_btt->id in case of failure and avoid double free, suggested
> by Dan Williams
> ---
> drivers/nvdimm/btt_devs.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
> index b72a303176c7..9486acc08402 100644
> --- a/drivers/nvdimm/btt_devs.c
> +++ b/drivers/nvdimm/btt_devs.c
> @@ -198,14 +198,15 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
> return NULL;
>
> nd_btt->id = ida_simple_get(&nd_region->btt_ida, 0, 0, GFP_KERNEL);
> - if (nd_btt->id < 0) {
> - kfree(nd_btt);
> - return NULL;
> - }
> + if (nd_btt->id < 0)
> + goto out_nd_btt;
>
> nd_btt->lbasize = lbasize;
> - if (uuid)
> + if (uuid) {
> uuid = kmemdup(uuid, 16, GFP_KERNEL);
> + if (!uuid)
> + goto out_put_id;
> + }
> nd_btt->uuid = uuid;
> dev = &nd_btt->dev;
> dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
> @@ -220,6 +221,13 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
> return NULL;
> }
> return dev;
> +
> +out_put_id:
> + ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
> +
> +out_nd_btt:
> + kfree(nd_btt);
> + return NULL;
> }
>
> struct device *nd_btt_create(struct nd_region *nd_region)


you have to take care of this below if block(true) as well as you are
touching the function.
 if (ndns && !__nd_attach_ndns(&nd_btt->dev, ndns, &nd_btt->ndns)) {

Thanks,
Mukesh

2019-03-26 18:32:54

by Dan Williams

Subject: Re: [PATCH v4] nvdimm: btt_devs: fix a NULL pointer dereference

On Tue, Mar 26, 2019 at 3:23 AM Mukesh Ojha <[email protected]> wrote:
>
>
> On 3/26/2019 3:25 AM, Aditya Pakki wrote:
> > In case kmemdup fails, the fix releases resources and returns to
> > avoid the NULL pointer dereference.
> >
> > Signed-off-by: Aditya Pakki <[email protected]>
> >
> > ---
> > v3: Move kfree(nd_btt) to goto block.
> > v2: Replace incorrect kfree with ida_simple_remove, suggested by
> > Johannes Thumshirn
> > v1: Free nd_btt->id in case of failure and avoid double free, suggested
> > by Dan Williams
> > ---
> > drivers/nvdimm/btt_devs.c | 18 +++++++++++++-----
> > 1 file changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
> > index b72a303176c7..9486acc08402 100644
> > --- a/drivers/nvdimm/btt_devs.c
> > +++ b/drivers/nvdimm/btt_devs.c
> > @@ -198,14 +198,15 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
> > return NULL;
> >
> > nd_btt->id = ida_simple_get(&nd_region->btt_ida, 0, 0, GFP_KERNEL);
> > - if (nd_btt->id < 0) {
> > - kfree(nd_btt);
> > - return NULL;
> > - }
> > + if (nd_btt->id < 0)
> > + goto out_nd_btt;
> >
> > nd_btt->lbasize = lbasize;
> > - if (uuid)
> > + if (uuid) {
> > uuid = kmemdup(uuid, 16, GFP_KERNEL);
> > + if (!uuid)
> > + goto out_put_id;
> > + }
> > nd_btt->uuid = uuid;
> > dev = &nd_btt->dev;
> > dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
> > @@ -220,6 +221,13 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
> > return NULL;
> > }
> > return dev;
> > +
> > +out_put_id:
> > + ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
> > +
> > +out_nd_btt:
> > + kfree(nd_btt);
> > + return NULL;
> > }
> >
> > struct device *nd_btt_create(struct nd_region *nd_region)
>
>
> you have to take care of this below if block(true) as well as you are
> touching the function.
> if (ndns && !__nd_attach_ndns(&nd_btt->dev, ndns, &nd_btt->ndns)) {

No, once the device is successfully initialized then put_device()
takes care of the rest.