[PATCH net] bnge: Fix NULL pointer dereference in aux device release

[Alok Tiwari <alok.a.tiwari@oracle.com>]

If allocation of auxr_dev fails during auxiliary device setup, the error
path calls auxiliary_device_uninit(), which eventually invokes
bnge_aux_dev_release().

The release callback unconditionally dereferences aux_priv->auxr_dev->pdev
to retrieve the parent bnge_dev. Since auxr_dev has not yet been allocated
on this failure path, the dereference results in a NULL pointer exception

Retrieve the parent bnge_dev from the auxiliary device's parent instead of
auxr_dev, and free auxr_dev only when it was successfully allocated. This
allows the release callback to correctly clean up partially initialized
auxiliary devices.

Fixes: 8ac050ec3b1c ("bng_en: Add RoCE aux device support")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
---
 drivers/net/ethernet/broadcom/bnge/bnge_auxr.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnge/bnge_auxr.c b/drivers/net/ethernet/broadcom/bnge/bnge_auxr.c
index 67e93e17d4d9..0955b488b6fe 100644
--- a/drivers/net/ethernet/broadcom/bnge/bnge_auxr.c
+++ b/drivers/net/ethernet/broadcom/bnge/bnge_auxr.c
@@ -141,12 +141,15 @@ static void bnge_aux_dev_release(struct device *dev)
 {
 	struct bnge_auxr_priv *aux_priv =
 			container_of(dev, struct bnge_auxr_priv, aux_dev.dev);
-	struct bnge_dev *bd = pci_get_drvdata(aux_priv->auxr_dev->pdev);
+	struct bnge_auxr_dev *auxr_dev = aux_priv->auxr_dev;
+	struct bnge_dev *bd = pci_get_drvdata(to_pci_dev(dev->parent));
 
 	ida_free(&bnge_aux_dev_ids, aux_priv->id);
-	kfree(aux_priv->auxr_dev->auxr_info);
+	if (auxr_dev) {
+		kfree(auxr_dev->auxr_info);
+		kfree(auxr_dev);
+	}
 	bd->auxr_dev = NULL;
-	kfree(aux_priv->auxr_dev);
 	kfree(aux_priv);
 	bd->aux_priv = NULL;
 }
-- 
2.52.0