[PATCH] net: mana: fix use-after-free in add_adev() error path

[PATCH] net: mana: fix use-after-free in add_adev() error path

[Guangshuo Li]

If auxiliary_device_add() fails, add_adev() calls
auxiliary_device_uninit(adev), whose release callback adev_release()
frees the containing struct mana_adev.

The current error path then falls through to init_fail and accesses
adev->id. Since adev is embedded in struct mana_adev, this may lead
to a use-after-free.

Fix it by storing the allocated auxiliary device id in a local
variable and using that saved id in the cleanup path after
auxiliary_device_uninit().

Fixes: a69839d4327d ("net: mana: Add support for auxiliary device")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/net/ethernet/microsoft/mana/mana_en.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index 1ad154f9db1a..70d71594c599 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -3362,6 +3362,7 @@ static int add_adev(struct gdma_dev *gd, const char *name)
 {
 	struct auxiliary_device *adev;
 	struct mana_adev *madev;
+	int id;
 	int ret;
 
 	madev = kzalloc(sizeof(*madev), GFP_KERNEL);
@@ -3372,7 +3373,8 @@ static int add_adev(struct gdma_dev *gd, const char *name)
 	ret = mana_adev_idx_alloc();
 	if (ret < 0)
 		goto idx_fail;
-	adev->id = ret;
+	id = ret;
+	adev->id = id;
 
 	adev->name = name;
 	adev->dev.parent = gd->gdma_context->dev;
@@ -3398,7 +3400,7 @@ static int add_adev(struct gdma_dev *gd, const char *name)
 	auxiliary_device_uninit(adev);
 
 init_fail:
-	mana_adev_idx_free(adev->id);
+	mana_adev_idx_free(id);
 
 idx_fail:
 	kfree(madev);
-- 
2.43.0

Re: [PATCH] net: mana: fix use-after-free in add_adev() error path

[Simon Horman]

On Wed, Mar 18, 2026 at 11:40:41PM +0800, Guangshuo Li wrote:
> If auxiliary_device_add() fails, add_adev() calls
> auxiliary_device_uninit(adev), whose release callback adev_release()
> frees the containing struct mana_adev.
> 
> The current error path then falls through to init_fail and accesses
> adev->id. Since adev is embedded in struct mana_adev, this may lead
> to a use-after-free.

It isn't clear to me how the use-after-free manifests.
Could you elaborate?

> 
> Fix it by storing the allocated auxiliary device id in a local
> variable and using that saved id in the cleanup path after
> auxiliary_device_uninit().
> 
> Fixes: a69839d4327d ("net: mana: Add support for auxiliary device")
> Cc: stable@vger.kernel.org
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>

As a bug fix for code present in the net tree, this patch
should be targeted at that tree like this.

Subject: [PATCH net] ...

And it should apply to that tree.

As it is the CI tries to apply this patch to the default tree, net-next.
Which fails. So there is no further CI performed.

> ---
>  drivers/net/ethernet/microsoft/mana/mana_en.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index 1ad154f9db1a..70d71594c599 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -3362,6 +3362,7 @@ static int add_adev(struct gdma_dev *gd, const char *name)
>  {
>  	struct auxiliary_device *adev;
>  	struct mana_adev *madev;
> +	int id;
>  	int ret;

Please preserve reverse xmas tree order for local variables - longest line
to shortest.

>  
>  	madev = kzalloc(sizeof(*madev), GFP_KERNEL);

...

-- 
pw-bot: changes-requested

RE: [EXTERNAL] [PATCH] net: mana: fix use-after-free in add_adev() error path

[Long Li]

> If auxiliary_device_add() fails, add_adev() calls auxiliary_device_uninit(adev),
> whose release callback adev_release() frees the containing struct mana_adev.
> 
> The current error path then falls through to init_fail and accesses
> adev->id. Since adev is embedded in struct mana_adev, this may lead
> to a use-after-free.
> 
> Fix it by storing the allocated auxiliary device id in a local variable and using that
> saved id in the cleanup path after auxiliary_device_uninit().
> 
> Fixes: a69839d4327d ("net: mana: Add support for auxiliary device")
> Cc: stable@vger.kernel.org
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>

Reviewed-by: Long Li <longli@microsoft.com>

Thank you.

> ---
>  drivers/net/ethernet/microsoft/mana/mana_en.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index 1ad154f9db1a..70d71594c599 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -3362,6 +3362,7 @@ static int add_adev(struct gdma_dev *gd, const char
> *name)  {
>         struct auxiliary_device *adev;
>         struct mana_adev *madev;
> +       int id;
>         int ret;
> 
>         madev = kzalloc(sizeof(*madev), GFP_KERNEL); @@ -3372,7 +3373,8 @@
> static int add_adev(struct gdma_dev *gd, const char *name)
>         ret = mana_adev_idx_alloc();
>         if (ret < 0)
>                 goto idx_fail;
> -       adev->id = ret;
> +       id = ret;
> +       adev->id = id;
> 
>         adev->name = name;
>         adev->dev.parent = gd->gdma_context->dev; @@ -3398,7 +3400,7 @@
> static int add_adev(struct gdma_dev *gd, const char *name)
>         auxiliary_device_uninit(adev);
> 
>  init_fail:
> -       mana_adev_idx_free(adev->id);
> +       mana_adev_idx_free(id);
> 
>  idx_fail:
>         kfree(madev);
> --
> 2.43.0