[PATCH] cxl: fix potential NULL dereference in free_adapter()

[Andrew Donnellan]

If kzalloc() fails when allocating adapter->guest in
cxl_guest_init_adapter(), we call free_adapter() before erroring out.
free_adapter() in turn attempts to dereference adapter->guest, which in
this case is NULL.

In free_adapter(), skip the adapter->guest cleanup if adapter->guest is
NULL.

Fixes: 14baf4d9c739 ("cxl: Add guest-specific code")
Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

---

Build tested only.
---
 drivers/misc/cxl/guest.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index ee7148e..9aa58a7 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c
@@ -1055,16 +1055,18 @@ static void free_adapter(struct cxl *adapter)
 	struct irq_avail *cur;
 	int i;
 
-	if (adapter->guest->irq_avail) {
-		for (i = 0; i < adapter->guest->irq_nranges; i++) {
-			cur = &adapter->guest->irq_avail[i];
-			kfree(cur->bitmap);
+	if (adapter->guest) {
+		if (adapter->guest->irq_avail) {
+			for (i = 0; i < adapter->guest->irq_nranges; i++) {
+				cur = &adapter->guest->irq_avail[i];
+				kfree(cur->bitmap);
+			}
+			kfree(adapter->guest->irq_avail);
 		}
-		kfree(adapter->guest->irq_avail);
+		kfree(adapter->guest->status);
+		kfree(adapter->guest);
 	}
-	kfree(adapter->guest->status);
 	cxl_remove_adapter_nr(adapter);
-	kfree(adapter->guest);
 	kfree(adapter);
 }
 
-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited