Hi Stefan,
On 15 June 2018 at 00:44, Stefan Johansson stefan.j.johansson@verisure.com wrote:
Hello, We have been looking at protecting U-Boot from (malicious) TFTP overwrites. We want to do this after our ARMv7 U-Boot has relocated.
The memory map looks like this (I hope):
--------------------------- Top of DRAM | U-Boot (Protected) | -------------------------- U_Boot_start | Heap (Protected) | -------------------------- Start_Heap = U_Boot_start - Heap_Size | Stack (Protected) | -------------------------- Start_Stack = Start_Heap - Stack_Size | Buffers (Protected) | -------------------------- ??? | Free DRAM (Not Protected) --------------------------- Start of DRAM
I seem to get lost in the code trying to find possible buffers, can you please give a hint how I can find the address "???"
Well gd->start_addr_sp is the stop of the stack. The size of the stack is not necessarily fixed and will grow downwards from there. But I suppose you could set a particular size and protect from start of DRAM to to the assumed bottom of the stack area.
Regards, Simon