git: e871598ad449 - main - libefivar: Check Length para before use in DevPathToTextUsbWWID

The branch main has been updated by imp:

URL: https://cgit.FreeBSD.org/src/commit/?id=e871598ad4493991404bbaa030f66bfe32aca892

commit e871598ad4493991404bbaa030f66bfe32aca892
Author:     Jose Luis Duran <jlduran@gmail.com>
AuthorDate: 2022-02-23 20:16:15 +0000
Commit:     Warner Losh <imp@FreeBSD.org>
CommitDate: 2022-02-27 16:13:40 +0000

    libefivar: Check Length para before use in DevPathToTextUsbWWID
    
    In function DevPathToTextUsbWWID, the Length parameter is used
    without check. This patch is to add check before using it.
    
    Upstream Bug:   https://bugzilla.tianocore.org/show_bug.cgi?id=1336
    Obtained from:  https://github.com/tianocore/edk2/commit/d8e702693a8c292220131dc4234a36e2c9fff614
    Pull Request:   https://github.com/freebsd/freebsd-src/pull/581
---
 lib/libefivar/efivar-dp-format.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/libefivar/efivar-dp-format.c b/lib/libefivar/efivar-dp-format.c
index 9c1969d81423..c3fa492d4c24 100644
--- a/lib/libefivar/efivar-dp-format.c
+++ b/lib/libefivar/efivar-dp-format.c
@@ -1033,7 +1033,7 @@ DevPathToTextUsbWWID (
 
   SerialNumberStr = (CHAR16 *) (&UsbWWId + 1);
   Length = (UINT16) ((DevicePathNodeLength ((EFI_DEVICE_PATH_PROTOCOL *) UsbWWId) - sizeof (USB_WWID_DEVICE_PATH)) / sizeof (CHAR16));
-  if (SerialNumberStr [Length - 1] != 0) {
+  if (Length >= 1 && SerialNumberStr [Length - 1] != 0) {
     //
     // In case no NULL terminator in SerialNumber, create a new one with NULL terminator
     //