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SubjectRe: [PATCH v2] nvdimm: btt_devs: fix a NULL pointer dereference
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On 23/03/2019 22:41, Aditya Pakki wrote:
> In case kmemdup fails, the fix releases resources and returns to
> avoid the NULL pointer dereference.
>
> Signed-off-by: Aditya Pakki <pakki001@umn.edu>
>
> ---
> v1: Free nd_btt->id in case of failure and avoid double free, suggested
> by Dan Williams
> ---
> 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 b72a303176c7..119a4ead2e46 100644
> --- a/drivers/nvdimm/btt_devs.c
> +++ b/drivers/nvdimm/btt_devs.c
> @@ -204,8 +204,14 @@ 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->id);
> + kfree(nd_btt);
> + return NULL;
> + }
> + }

nd_btt->id is an ida and thus must be freed using:
ida_simple_remove(&nd_region->btt_ida, nd_btt->id);

that being I'd prefer a 'out_put_id' label at the end of the function
and to the cleanups there.

Something like this:

if (uuid) {
uuid = kmemdup(uuid, 16, GFP_KERNEL);
if (!uuid)
goto out_put_id;

[...]

return dev;

out_put_id:
ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
kfree(nd_btt);
return NULL;
}


--
Johannes Thumshirn SUSE Labs Filesystems
jthumshirn@suse.de +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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