From: Mario Limonciello <mario.limonciello@xxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx> Acked-by: Yehezkel Bernat <YehezkelShB@xxxxxxxxx> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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)