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util/cbfstool: Improve heuristic for cbfs header pointer protection 

cbfstool has a routine to deal with old images that may encourage it to
overwrite the master header. That routine is triggered for
"cbfstool add-master-header" prepared images even though these are not
at risk, and - worse - destroys the chain structure (through a negative
file length), so avoid touching such images.

Change-Id: I9d0bbe3e6300b9b9f3e50347737d1850f83ddad8
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: https://review.coreboot.org/13672
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
This commit is contained in:
Patrick Georgi 2016-02-10 18:07:52 +01:00 committed by Patrick Georgi
parent 0a07c5c4a0
commit 343ea08388
1 changed files with 7 additions and 0 deletions
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7
util/cbfstool/cbfs_image.c
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@ -110,11 +110,18 @@ static int cbfs_fix_legacy_size(struct cbfs_image *image, char *hdr_loc)
// A bug in old cbfstool may produce extra few bytes (by alignment) and
// cause cbfstool to overwrite things after free space -- which is
// usually CBFS header on x86. We need to workaround that.
// Except when we run across a file that contains the actual header,
// in which case this image is a safe, new-style
// `cbfstool add-master-header` based image.
struct cbfs_file *entry, *first = NULL, *last = NULL;
for (first = entry = cbfs_find_first_entry(image);
entry && cbfs_is_valid_entry(image, entry);
entry = cbfs_find_next_entry(image, entry)) {
/* Is the header guarded by a CBFS file entry? Then exit */
if (((char *)entry) + ntohl(entry->offset) == hdr_loc) {
return 0;
}
last = entry;
}
if ((char *)first < (char *)hdr_loc &&