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

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

Posted by Zhaoyang Yu 1 week, 5 days ago

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 <2426767509@qq.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);
-- 
2.34.1

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

Posted by Ira Weiny 1 week, 5 days ago

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 <2426767509@qq.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;
> +	}

Sorry this is a NAK.

While I don't like the implicit nature of the check...  This is not
needed.

The validity of pfn_sb is checked in nd_pfn_validate()

It is unfortunate that the errno reported in that case is ENODEV rather
than ENOMEM...  But I would not change that now.

>  	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);

Same issue here.

Ira

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

Posted by 俞朝阳 1 week, 5 days ago

Hi Ira,

Thanks for the detailed explanation.

I see now that nd_pfn_validate() already handles the NULL pfn_sb case, and the error path correctly releases the device. You are right that the patch is unnecessary.

I will drop this patch. Thanks for your time reviewing it.

Best regards,
Zhaoyang



原始邮件
发件人：Ira Weiny <ira.weiny@intel.com>
发件时间：2026年1月27日 04:27
收件人：Zhaoyang Yu <2426767509@qq.com>, dan.j.williams <dan.j.williams@intel.com>
抄送：vishal.l.verma <vishal.l.verma@intel.com>, dave.jiang <dave.jiang@intel.com>, ira.weiny <ira.weiny@intel.com>, nvdimm <nvdimm@lists.linux.dev>, linux-kernel <linux-kernel@vger.kernel.org>, gszhai <gszhai@bjtu.edu.cn>, Zhaoyang Yu <2426767509@qq.com>
主题：Re: [PATCH] nvdimm: Add check for devm_kmalloc() and fix NULLpointer dereference in nd_pfn_probe() and nd_dax_probe()


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 <2426767509@qq.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;
> + }

Sorry this is a NAK.

While I don't like the implicit nature of the check...  This is not
needed.

The validity of pfn_sb is checked in nd_pfn_validate()

It is unfortunate that the errno reported in that case is ENODEV rather
than ENOMEM...  But I would not change that now.

>   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);

Same issue here.

Ira

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

Posted by Dave Jiang 1 week, 5 days ago


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 <2426767509@qq.com>

Please provide a Fixes tag. Otherwise LGTM.

Reviewed-by: Dave Jiang <dave.jiang@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);