libdwfl: Use memcpy to assign image header field values

The values in the kernel image header aren't properly aligned.
Use memcpy and the LE16, LE32 macros to assign and check the
values.

Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 182f4e34bee9fea9b7e099af4d826964569fcea2..9c5c85178834f540a6f4ec6d9fabd739da672e0d 100644 (file)
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,8 @@
+2022-02-18  Mark Wielaard  <mark@klomp.org>
+
+       * image-header.c (__libdw_image_header): Assign header values for
+       magic1, magic2, version, offset, length and sects using memcpy.
+
 2022-02-18  Mark Wielaard  <mark@klomp.org>
 
        * offline.c (process_archive_member): Close member if process_file

diff --git a/libdwfl/image-header.c b/libdwfl/image-header.c
index 25fbfd999c8139b978061979512a827410535034..f906068ab50a4ab2f18ad8a7eed45d529be22851 100644 (file)
--- a/libdwfl/image-header.c
+++ b/libdwfl/image-header.c
@@ -1,5 +1,6 @@
 /* Linux kernel image support for libdwfl.
    Copyright (C) 2009-2011 Red Hat, Inc.
+   Copyright (C) 2022 Mark J. Wielaard <mark@klomp.org>
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -80,17 +81,28 @@ __libdw_image_header (int fd, off_t *start_offset,
          header = header_buffer - H_START;
        }
 
-      if (*(uint16_t *) (header + H_MAGIC1) == LE16 (MAGIC1)
-         && *(uint32_t *) (header + H_MAGIC2) == LE32 (MAGIC2)
-         && LE16 (*(uint16_t *) (header + H_VERSION)) >= MIN_VERSION)
+      uint16_t magic1;
+      uint32_t magic2;
+      uint16_t version;
+      memcpy (&magic1, header + H_MAGIC1, sizeof (uint16_t));
+      memcpy (&magic2, header + H_MAGIC2, sizeof (uint32_t));
+      memcpy (&version, header + H_VERSION, sizeof (uint16_t));
+      if (magic1 == LE16 (MAGIC1) && magic2 == LE32 (MAGIC2)
+         && LE16 (version) >= MIN_VERSION)
        {
          /* The magic numbers match and the version field is sufficient.
             Extract the payload bounds.  */
 
-         uint32_t offset = LE32 (*(uint32_t *) (header + H_PAYLOAD_OFFSET));
-         uint32_t length = LE32 (*(uint32_t *) (header + H_PAYLOAD_LENGTH));
+         uint32_t offset;
+         uint32_t length;
+         uint8_t sects;
+         memcpy (&offset, header + H_PAYLOAD_OFFSET, sizeof (uint32_t));
+         memcpy (&length, header + H_PAYLOAD_LENGTH, sizeof (uint32_t));
+         memcpy (&sects, header + H_SETUP_SECTS, sizeof (uint8_t));
+         offset = LE32 (offset);
+         length = LE32 (length);
 
-         offset += ((*(uint8_t *) (header + H_SETUP_SECTS) ?: 4) + 1) * 512;
+         offset += ((sects ?: 4) + 1) * 512;
 
          if (offset > H_END && offset < mapped_size
              && mapped_size - offset >= length)