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SubjectRe: [PATCH] nvdimm: btt_devs: fix a NULL pointer dereference and a memory leak
On Tue, Mar 12, 2019 at 1:16 AM Kangjie Lu <kjlu@umn.edu> wrote:
>
> In case kmemdup fails, the fix releases resources and returns to
> avoid the NULL pointer dereference.
> Also, the error paths in the following code should release
> resources to avoid memory leaks.
>
> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
> ---
> drivers/nvdimm/btt_devs.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
> index 795ad4ff35ca..565ea0b6f765 100644
> --- a/drivers/nvdimm/btt_devs.c
> +++ b/drivers/nvdimm/btt_devs.c
> @@ -196,8 +196,13 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
> }
>
> nd_btt->lbasize = lbasize;
> - if (uuid)
> + if (uuid) {
> uuid = kmemdup(uuid, 16, GFP_KERNEL);
> + if (!uuid) {
> + kfree(nd_btt);
> + return NULL;

What about nd_btt->id? That needs to be released as well.

> + }
> + }
> nd_btt->uuid = uuid;
> dev = &nd_btt->dev;
> dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
> @@ -209,6 +214,7 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
> dev_dbg(&ndns->dev, "failed, already claimed by %s\n",
> dev_name(ndns->claim));
> put_device(dev);
> + kfree(uuid);

This will be a double free because put_device() will arrange for
nd_btt_release() to be called which does kfree(nd_btt->uuid);

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