The libfdt functions are supposed to behave tolerably well when practical,
even if given a corrupted device tree as input. A silly mistake in
fdt_get_property() means we're bounds checking against the size of a pointer
instead of the size of a property header, meaning we can get bogus
behaviour in a corrupted device tree where the structure block ends in
what's supposed to be the middle of a property.
This patch corrects the problem (fdt_get_property() will now return
BADSTRUCTURE in this case), and also adds a testcase to catch the bug.
This patch fixes a number of embarrasing oversights which meant libfdt
did not work correctly on little endian machines. With this patch the
testsuite now passes on x86. Device trees are always created
big-endian.
v17 of the blob format adds a field for the size of the structure
block, but is backwards compatible with v16. This patch introduces
definitions for the new field, and uses it to improve the bounds
checking in the read-only code. It also cleans up the sequential
write code using it: we no longer need to borrow the version field as
a write pointer.
David Gibson