thunderbolt: Fix possible NULL pointer dereference in tb_acpi_add_link()

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>

diff --git a/drivers/thunderbolt/acpi.c b/drivers/thunderbolt/acpi.c
index a5f988a9f9482bd54eef3f96cce4928c42ee02a5..b5442f979b4d0170950d9ded3d3dbe9e3066d6da 100644 (file)
--- a/drivers/thunderbolt/acpi.c
+++ b/drivers/thunderbolt/acpi.c
@@ -56,7 +56,7 @@ static acpi_status tb_acpi_add_link(acpi_handle handle, u32 level, void *data,
         * 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)