From 098058752e1cee7b457ff45562a81e756ab0b532 Mon Sep 17 00:00:00 2001
From: Daniel Kiper <daniel.kiper@oracle.com>
Date: Wed, 29 Jul 2020 13:38:31 +0200
Subject: [PATCH 24/27] efi/chainloader: Propagate errors from copy_file_path()

Without any error propagated to the caller, make_file_path()
would then try to advance the invalid device path node with
GRUB_EFI_NEXT_DEVICE_PATH(), which would fail, returning a NULL
pointer that would subsequently be dereferenced. Hence, propagate
errors from copy_file_path().

Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 grub-core/loader/efi/chainloader.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
index 9a99f04..813dc0e 100644
--- a/grub-core/loader/efi/chainloader.c
+++ b/grub-core/loader/efi/chainloader.c
@@ -115,7 +115,7 @@ grub_chainloader_boot (void)
   return grub_errno;
 }
 
-static void
+static grub_err_t
 copy_file_path (grub_efi_file_path_device_path_t *fp,
 		const char *str, grub_efi_uint16_t len)
 {
@@ -127,7 +127,7 @@ copy_file_path (grub_efi_file_path_device_path_t *fp,
 
   path_name = grub_calloc (len, GRUB_MAX_UTF16_PER_UTF8 * sizeof (*path_name));
   if (!path_name)
-    return;
+    return grub_error (GRUB_ERR_OUT_OF_MEMORY, "failed to allocate path buffer");
 
   size = grub_utf8_to_utf16 (path_name, len * GRUB_MAX_UTF16_PER_UTF8,
 			     (const grub_uint8_t *) str, len, 0);
@@ -140,6 +140,7 @@ copy_file_path (grub_efi_file_path_device_path_t *fp,
   fp->path_name[size++] = '\0';
   fp->header.length = size * sizeof (grub_efi_char16_t) + sizeof (*fp);
   grub_free (path_name);
+  return GRUB_ERR_NONE;
 }
 
 static grub_efi_device_path_t *
@@ -197,13 +198,19 @@ make_file_path (grub_efi_device_path_t *dp, const char *filename)
   /* Fill the file path for the directory.  */
   d = (grub_efi_device_path_t *) ((char *) file_path
 				  + ((char *) d - (char *) dp));
-  copy_file_path ((grub_efi_file_path_device_path_t *) d,
-		  dir_start, dir_end - dir_start);
+  if (copy_file_path ((grub_efi_file_path_device_path_t *) d,
+		  dir_start, dir_end - dir_start) != GRUB_ERR_NONE)
+    {
+fail:
+     grub_free(file_path);
+     return 0;
+    }
 
   /* Fill the file path for the file.  */
   d = GRUB_EFI_NEXT_DEVICE_PATH (d);
-  copy_file_path ((grub_efi_file_path_device_path_t *) d,
-		  dir_end + 1, grub_strlen (dir_end + 1));
+  if (copy_file_path ((grub_efi_file_path_device_path_t *) d,
+		  dir_end + 1, grub_strlen (dir_end + 1)) != GRUB_ERR_NONE)
+      goto fail;
 
   /* Fill the end of device path nodes.  */
   d = GRUB_EFI_NEXT_DEVICE_PATH (d);
-- 
2.23.0

