[PATCH 5.10 053/120] thunderbolt: Fix possible NULL pointer dereference in tb_acpi_add_link()

Greg Kroah-Hartman
2021-02-08T17:08:31Z

From: Mario Limonciello <mario.limonciello@dell.com>

commit 4d395c5e74398f664405819330e5a298da37f655 upstream.

When we walk up the device hierarchy in tb_acpi_add_link() make sure we
break the loop if the device has no parent. Otherwise we may crash the
kernel by dereferencing a NULL pointer.

Fixes: b2be2b05cf3b ("thunderbolt: Create device links from ACPI description")
Cc: stable@vger.kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/thunderbolt/acpi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/thunderbolt/acpi.c
+++ b/drivers/thunderbolt/acpi.c
@@ -56,7 +56,7 @@ static acpi_status tb_acpi_add_link(acpi
* managed with the xHCI and the SuperSpeed hub so we create the
* link from xHCI instead.
*/
- while (!dev_is_pci(dev))
+ while (dev && !dev_is_pci(dev))
dev = dev->parent;

if (!dev)