2021-04-10 01:05:44

by Yingjie Wang

Subject: [PATCH v1] libnvdimm, dax: Fix a missing check in nd_dax_probe()

From: Yingjie Wang <[email protected]>

In nd_dax_probe(), nd_dax_alloc() may fail and return NULL.
Check for NULL before attempting to
use nd_dax to avoid a NULL pointer dereference.

Fixes: c5ed9268643c ("libnvdimm, dax: autodetect support")
Signed-off-by: Yingjie Wang <[email protected]>
---
drivers/nvdimm/dax_devs.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c
index 99965077bac4..b1426ac03f01 100644
--- a/drivers/nvdimm/dax_devs.c
+++ b/drivers/nvdimm/dax_devs.c
@@ -106,6 +106,8 @@ int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns)

nvdimm_bus_lock(&ndns->dev);
nd_dax = nd_dax_alloc(nd_region);
+ if (!nd_dax)
+ return -ENOMEM;
nd_pfn = &nd_dax->nd_pfn;
dax_dev = nd_pfn_devinit(nd_pfn, ndns);
nvdimm_bus_unlock(&ndns->dev);
--
2.7.4

2021-04-10 04:56:59

by Dan Williams

Subject: Re: [PATCH v1] libnvdimm, dax: Fix a missing check in nd_dax_probe()

On Fri, Apr 9, 2021 at 5:33 PM <[email protected]> wrote:
>
> From: Yingjie Wang <[email protected]>
>
> In nd_dax_probe(), nd_dax_alloc() may fail and return NULL.
> Check for NULL before attempting to
> use nd_dax to avoid a NULL pointer dereference.
>
> Fixes: c5ed9268643c ("libnvdimm, dax: autodetect support")
> Signed-off-by: Yingjie Wang <[email protected]>
> ---
> drivers/nvdimm/dax_devs.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c
> index 99965077bac4..b1426ac03f01 100644
> --- a/drivers/nvdimm/dax_devs.c
> +++ b/drivers/nvdimm/dax_devs.c
> @@ -106,6 +106,8 @@ int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns)
>
> nvdimm_bus_lock(&ndns->dev);

hmmm...

> nd_dax = nd_dax_alloc(nd_region);
> + if (!nd_dax)
> + return -ENOMEM;

Can you spot the bug this introduces? See the hint above.

> nd_pfn = &nd_dax->nd_pfn;
> dax_dev = nd_pfn_devinit(nd_pfn, ndns);
> nvdimm_bus_unlock(&ndns->dev);
> --
> 2.7.4
>