[PATCH v2 3/4] ata: libata-transport: fix error handling in ata_tlink_add()

[Yang Yingliang <yangyingliang@huawei.com>]

In ata_tlink_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: 33 PID: 13850 Comm: rmmod Kdump: loaded Tainted: G        W          6.1.0-rc3+ #12
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+0x88/0xb0 [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_tlink_add().

Fixes: d9027470b886 ("[libata] Add ATA transport class")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/ata/libata-transport.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-transport.c b/drivers/ata/libata-transport.c
index ef53bdfbcbb2..aac9336e8153 100644
--- a/drivers/ata/libata-transport.c
+++ b/drivers/ata/libata-transport.c
@@ -458,7 +458,9 @@ int ata_tlink_add(struct ata_link *link)
 		goto tlink_err;
 	}
 
-	transport_add_device(dev);
+	error = transport_add_device(dev);
+	if (error)
+		goto tlink_transport_err;
 	transport_configure_device(dev);
 
 	ata_for_each_dev(ata_dev, link, ALL) {
@@ -473,6 +475,7 @@ int ata_tlink_add(struct ata_link *link)
 		ata_tdev_delete(ata_dev);
 	}
 	transport_remove_device(dev);
+  tlink_transport_err:
 	device_del(dev);
   tlink_err:
 	transport_destroy_device(dev);
-- 
2.25.1