[PATCH] EDAC/versalnet: Fix resource leaks and NULL derefs in init_versalnet()

[Eric-Terminal <ericterminal@gmail.com>]

From: Yufan Chen <ericterminal@gmail.com>

init_versalnet() has several bugs in its error handling:

 - kzalloc() and kmalloc() return values are used without NULL checks,
   causing a NULL pointer dereference when allocation fails.

 - The cleanup loop uses while (i--) which skips the current failing
   index, leaking the resources already allocated for that slot.

 - edac_mc_del_mc() is called unconditionally during unwind, even for
   controllers that were never registered with edac_mc_add_mc().

 - sprintf() is used instead of snprintf() on a fixed-size buffer.

Fix by adding NULL checks for dev and name allocations, replacing
while (i--) with for (j = i; j >= 0; j--) to include the failing
index, tracking successful edac_mc_add_mc() calls with a bool array,
and switching to snprintf().

Signed-off-by: Yufan Chen <ericterminal@gmail.com>
---
 drivers/edac/versalnet_edac.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/edac/versalnet_edac.c b/drivers/edac/versalnet_edac.c
index 1a1092793..128e9cd5f 100644
--- a/drivers/edac/versalnet_edac.c
+++ b/drivers/edac/versalnet_edac.c
@@ -764,11 +764,12 @@ static int init_versalnet(struct mc_priv *priv, struct platform_device *pdev)
 {
 	u32 num_chans, rank, dwidth, config;
 	struct edac_mc_layer layers[2];
+	bool mc_added[NUM_CONTROLLERS] = { };
 	struct mem_ctl_info *mci;
 	struct device *dev;
 	enum dev_type dt;
 	char *name;
-	int rc, i;
+	int rc, i, j;
 
 	for (i = 0; i < NUM_CONTROLLERS; i++) {
 		config = priv->adec[CONF + i * ADEC_NUM];
@@ -813,11 +814,25 @@ static int init_versalnet(struct mc_priv *priv, struct platform_device *pdev)
 		priv->dwidth = dt;
 
 		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+		if (!dev) {
+			rc = -ENOMEM;
+			goto err_alloc;
+		}
+
 		dev->release = versal_edac_release;
 		name = kmalloc(32, GFP_KERNEL);
-		sprintf(name, "versal-net-ddrmc5-edac-%d", i);
+		if (!name) {
+			kfree(dev);
+			rc = -ENOMEM;
+			goto err_alloc;
+		}
+
+		snprintf(name, 32, "versal-net-ddrmc5-edac-%d", i);
 		dev->init_name = name;
 		rc = device_register(dev);
+		kfree(name);
+		if (rc)
+			put_device(dev);
 		if (rc)
 			goto err_alloc;
 
@@ -831,21 +846,25 @@ static int init_versalnet(struct mc_priv *priv, struct platform_device *pdev)
 			edac_printk(KERN_ERR, EDAC_MC, "Failed to register MC%d with EDAC core\n", i);
 			goto err_alloc;
 		}
+
+		mc_added[i] = true;
 	}
 	return 0;
 
 err_alloc:
-	while (i--) {
-		mci = priv->mci[i];
+	for (j = i; j >= 0; j--) {
+		mci = priv->mci[j];
 		if (!mci)
 			continue;
 
 		if (mci->pdev) {
 			device_unregister(mci->pdev);
-			edac_mc_del_mc(mci->pdev);
+			if (mc_added[j])
+				edac_mc_del_mc(mci->pdev);
 		}
 
 		edac_mc_free(mci);
+		priv->mci[j] = NULL;
 	}
 
 	return rc;
-- 
2.47.3