e820_add_entry_cb() appended every FSP-supplied resource descriptor into
boot_params->e820_table[] with no check against E820_MAX_ENTRIES_ZEROPAGE
(128). A HOB list with more than 128 EFI_HOB_TYPE_RESOURCE_DESCRIPTOR
entries therefore wrote FSP-controlled addr/size/type triples past the
fixed-size table into the stack-allocated boot_params in load_linux(),
corrupting adjacent fields and the saved return address.
Reject any entry once the table is full (return non-zero, which aborts the
HOB iteration). e820_entries stays uint8_t since it is a fixed-offset field
in the Linux zero-page layout and the cap makes the 256 wrap unreachable.
Add unit-linux-loader-e820 regression test (x86 32bit, standalone) that
feeds 200 descriptors and asserts the table never overflows.
Daniele Lacamera