[PATCH v2 4/4] ata: libata-transport: fix error handling in ata_tdev_add()

[Yang Yingliang <yangyingliang@huawei.com>]

In ata_tdev_add(), the return value of transport_add_device() is not
checked. As a result, another error after that function call leads to
a kernel crash (null-ptr-deref) because transport_remove_device() is
called to remove a device that was not added.

Unable to handle kernel NULL pointer dereference at virtual address 00000000000000d0
CPU: 61 PID: 13969 Comm: rmmod Kdump: loaded Tainted: G        W          6.1.0-rc3+ #13
pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : device_del+0x48/0x39c
lr : device_del+0x44/0x39c
Call trace:
 device_del+0x48/0x39c
 attribute_container_class_device_del+0x28/0x40
 transport_remove_classdev+0x60/0x7c
 attribute_container_device_trigger+0x118/0x120
 transport_remove_device+0x20/0x30
 ata_tlink_delete+0x4c/0xb0 [libata]
 ata_tport_delete+0x2c/0x60 [libata]
 ata_port_detach+0x148/0x1b0 [libata]
 ata_pci_remove_one+0x50/0x80 [libata]
 ahci_remove_one+0x4c/0x8c [ahci]

Fix this by checking and handling return value of transport_add_device()
in ata_tdev_add().

Fixes: d9027470b886 ("[libata] Add ATA transport class")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/ata/libata-transport.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-transport.c b/drivers/ata/libata-transport.c
index aac9336e8153..e4fb9d1b9b39 100644
--- a/drivers/ata/libata-transport.c
+++ b/drivers/ata/libata-transport.c
@@ -713,7 +713,13 @@ static int ata_tdev_add(struct ata_device *ata_dev)
 		return error;
 	}
 
-	transport_add_device(dev);
+	error = transport_add_device(dev);
+	if (error) {
+		device_del(dev);
+		ata_tdev_free(ata_dev);
+		return error;
+	}
+
 	transport_configure_device(dev);
 	return 0;
 }
-- 
2.25.1