From 14d63398298c8de23036a4cf61594108b7345863 Mon Sep 17 00:00:00 2001
From: Robbie Harwood <rharwood@redhat.com>
Date: Tue, 23 Aug 2022 12:07:16 -0400
Subject: [PATCH 05/13] Discard load-options that start with a NUL
In 6c8d08c0af4768c715b79c8ec25141d56e34f8b4 ("shim: Ignore UEFI
LoadOptions that are just NUL characters."), a check was added to
discard load options that are entirely NUL. We now see some firmwares
that start LoadOptions with a NUL, and then follow it with garbage (path
to directory containing loaders). Widen the check to just discard
anything that starts with a NUL.
Resolves: #490
Related: #95
See-also: https://bugzilla.redhat.com/show_bug.cgi?id=2113005
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
---
load-options.c | 7 ++++++-
include/ucs2.h | 18 ------------------
2 files changed, 6 insertions(+), 19 deletions(-)
diff --git a/load-options.c b/load-options.c
index c6bb7427685..a8c6e1a3d37 100644
--- a/load-options.c
+++ b/load-options.c
@@ -404,8 +404,13 @@ parse_load_options(EFI_LOADED_IMAGE *li)
/*
* Apparently sometimes we get L"\0\0"? Which isn't useful at all.
+ *
+ * Possibly related, but some boards have additional data before the
+ * size which is garbage (it's a weird path to the directory
+ * containing the loaders). Known boards that do this: Kontron VX3040
+ * (AMI), ASUS B85M-E, and at least one "older Dell laptop".
*/
- if (is_all_nuls(li->LoadOptions, li->LoadOptionsSize))
+ if (((CHAR16 *)li->LoadOptions)[0] == 0)
return EFI_SUCCESS;
/*
diff --git a/include/ucs2.h b/include/ucs2.h
index ee038ce798a..87eab32f006 100644
--- a/include/ucs2.h
+++ b/include/ucs2.h
@@ -63,22 +63,4 @@ StrCSpn(const CHAR16 *s, const CHAR16 *reject)
return ret;
}
-/*
- * Test if an entire buffer is nothing but NUL characters. This
- * implementation "gracefully" ignores the difference between the
- * UTF-8/ASCII 1-byte NUL and the UCS-2 2-byte NUL.
- */
-static inline bool
-__attribute__((__unused__))
-is_all_nuls(UINT8 *data, UINTN data_size)
-{
- UINTN i;
-
- for (i = 0; i < data_size; i++) {
- if (data[i] != 0)
- return false;
- }
- return true;
-}
-
#endif /* SHIM_UCS2_H */
--
2.37.1