tree cd0af77dfc2b34ebf26977b11dc2d7fdf7654502
parent 198f39a4d63bdeb89ac3e07f207f1451730e58ce
author Konrad Beckmann <konrad.beckmann@gmail.com> 1541620306 -0500
committer Tom Rini <trini@konsulko.com> 1542405121 -0500

fdt_region: Ensure that depth never goes below -1

A specially crafted FIT image makes it possible to overflow the stack
with controlled values when using the verified boot feature. Depending
on the memory layout, this could be used to overwrite configuration
variables on the heap and setting them to 0, e.g. disable signature
verification, thus bypassing it.

This change fixes a bug in fdt_find_regions where the fdt structure is
parsed. A lower value than -1 of depth can lead to a buffer underflow
write on the stack.

Signed-off-by: Konrad Beckmann <konrad.beckmann@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>