From 79be2af5260b1f2e2a4680e74e14da0fdb42b570 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Fri, 7 Sep 2018 14:11:02 +0200
Subject: [PATCH 13/62] shim: Properly generate absolute paths from relative
 image paths

The generate_path_from_image_path() doesn't properly handle the case when
shim is invoked using a relative path (e.g: from the EFI shell). In that
function, always the last component is stripped from absolute file path
to calculate the dirname, and this is concatenated with the image path.

But if the path is a relative one, the function will wrongly concatenate
the dirname with the relative image path, i.e:

 Shell> FS0:
 FS0:\> cd EFI
 FS0:\EFI\> BOOT\BOOTX64.EFI
 Failed to open \EFI\BOOT\BOOT\BOOTX64.EFI - Not found
 Failed to load image \EFI\BOOT\BOOT\BOOTX64.EFI: Not found
 start_image() returned Not found

Calculate the image path basename and concatenate that with the dirname.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Maran Wilson maran.wilson@oracle.com
Tested-by: Maran Wilson maran.wilson@oracle.com
Upstream-commit-id: a625fa5096c
---
 shim.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/shim.c b/shim.c
index 05fc65005d1..5ab23d03db4 100644
--- a/shim.c
+++ b/shim.c
@@ -1610,9 +1610,11 @@ static EFI_STATUS generate_path_from_image_path(EFI_LOADED_IMAGE *li,
 		bootpath[j] = '\0';
 	}
 
-	while (*ImagePath == '\\')
-		ImagePath++;
+	for (i = 0, last = 0; i < StrLen(ImagePath); i++)
+		if (ImagePath[i] == '\\')
+			last = i + 1;
 
+	ImagePath = ImagePath + last;
 	*PathName = AllocatePool(StrSize(bootpath) + StrSize(ImagePath));
 
 	if (!*PathName) {
-- 
2.26.2