Re: [PATCH] nvdimm: Add check for devm_kmalloc() and fix NULL pointer dereference in nd_pfn_probe() and nd_dax_probe()

[Dave Jiang]

On 1/26/26 6:04 AM, Zhaoyang Yu wrote:
> The devm_kmalloc() function may return NULL when memory allocation fails.
> In nd_pfn_probe() and nd_dax_probe(), the return values of devm_kmalloc()
> are not checked. If pfn_sb is NULL, it will cause a NULL pointer
> dereference in the subsequent calls to nd_pfn_validate().
> 
> Additionally, if the allocation fails, the devices initialized by
> nd_pfn_devinit() or nd_dax_devinit() are not properly released, leading
> to memory leaks.
> 
> Fix this by checking the return value of devm_kmalloc() in both functions.
> If the allocation fails, use put_device() to release the initialized device
> and return -ENOMEM.
> 
> Signed-off-by: Zhaoyang Yu <2426767...@qq.com>

Please provide a Fixes tag. Otherwise LGTM.

Reviewed-by: Dave Jiang <dave.ji...@intel.com>

> ---
>  drivers/nvdimm/dax_devs.c | 4 ++++
>  drivers/nvdimm/pfn_devs.c | 4 ++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c
> index ba4c409ede65..aa51a9022d12 100644
> --- a/drivers/nvdimm/dax_devs.c
> +++ b/drivers/nvdimm/dax_devs.c
> @@ -111,6 +111,10 @@ int nd_dax_probe(struct device *dev, struct 
> nd_namespace_common *ndns)
>                       return -ENOMEM;
>       }
>       pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
> +     if (!pfn_sb) {
> +             put_device(dax_dev);
> +             return -ENOMEM;
> +     }
>       nd_pfn = &nd_dax->nd_pfn;
>       nd_pfn->pfn_sb = pfn_sb;
>       rc = nd_pfn_validate(nd_pfn, DAX_SIG);
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index 42b172fc5576..6a69d8bfeb7c 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -635,6 +635,10 @@ int nd_pfn_probe(struct device *dev, struct 
> nd_namespace_common *ndns)
>       if (!pfn_dev)
>               return -ENOMEM;
>       pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
> +     if (!pfn_sb) {
> +             put_device(pfn_dev);
> +             return -ENOMEM;
> +     }
>       nd_pfn = to_nd_pfn(pfn_dev);
>       nd_pfn->pfn_sb = pfn_sb;
>       rc = nd_pfn_validate(nd_pfn, PFN_SIG);