[PATCH] pci: endpoint: Add missing NULL check for alloc_workqueue()

[Haotian Zhang]

The alloc_workqueue() function can return NULL on memory allocation
failure. Without proper error checking, this leads to a NULL pointer
dereference when queue_work() is later called with the NULL workqueue
pointer in epf_ntb_epc_init().

Add a NULL check immediately after alloc_workqueue() and return -ENOMEM
on failure to prevent the driver from loading with an invalid workqueue
pointer.

Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Fixes: 8b821cf76150 ("PCI: endpoint: Add EP function driver to provide NTB functionality")
Signed-off-by: Haotian Zhang <vulab@xxxxxxxxxxx>
---
 drivers/pci/endpoint/functions/pci-epf-ntb.c  | 4 ++++
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-ntb.c b/drivers/pci/endpoint/functions/pci-epf-ntb.c
index e01a98e74d21..b3d96a2e3a8c 100644
--- a/drivers/pci/endpoint/functions/pci-epf-ntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-ntb.c
@@ -2126,6 +2126,10 @@ static int __init epf_ntb_init(void)
 
 	kpcintb_workqueue = alloc_workqueue("kpcintb", WQ_MEM_RECLAIM |
 					    WQ_HIGHPRI, 0);
+	if (!kpcintb_workqueue) {
+		pr_err("Failed to allocate kpcintb workqueue\n");
+		return -ENOMEM;
+	}
 	ret = pci_epf_register_driver(&epf_ntb_driver);
 	if (ret) {
 		destroy_workqueue(kpcintb_workqueue);
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 83e9ab10f9c4..79800f1fecc3 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -1534,6 +1534,10 @@ static int __init epf_ntb_init(void)
 
 	kpcintb_workqueue = alloc_workqueue("kpcintb", WQ_MEM_RECLAIM |
 					    WQ_HIGHPRI, 0);
+	if (!kpcintb_workqueue) {
+		pr_err("Failed to allocate kpcintb workqueue\n");
+		return -ENOMEM;
+	}
 	ret = pci_epf_register_driver(&epf_ntb_driver);
 	if (ret) {
 		destroy_workqueue(kpcintb_workqueue);
-- 
2.50.1.windows.1