Vector35 / Vector35/binaryninja-api
Binja incorrectly translating ILP32 tailcall pattern
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Description
Bug Description:
Binja incorrectly translating AArch64 ILP32 tailcall pattern as a result of 32-bit load into w17 and jump through x17.
00401dc0 uint32_t strtoul(char const* str, char** endptr, int32_t base)
00401dc0 adrp x16, getspnam
00401dc4 ldr w17, [x16, #0x10c] {strtoul}
00401dc8 add w16, w16, #0x10c {strtoul}
❓00401dcc br x17
Steps To Reproduce:
Please provide all steps required to reproduce the behavior:
- Open the attached binary in Binja 5.3.9025 or later
- Navigate to
strtoulin.plt - Observe the tag at
0x401dccon thejump(zx.q(*getaddrinfo))
Expected Behavior:
Translate correctly resulting in x17 being a resolved constant value
Binary:
victory spring enters valuably
Additional Information:
This hack allows the PLT branches to the extern region to work fine, but this isn't a good solution and I think we need to fix this in core.
diff --git a/arch/arm64/il.cpp b/arch/arm64/il.cpp
index f02cdd2d..ab6ff084 100644
--- a/arch/arm64/il.cpp
+++ b/arch/arm64/il.cpp
@@ -905,8 +905,11 @@ static void LoadStoreOperand(LowLevelILFunction& il, bool load,
ILSETREG_O(operand1, il.Operand(1, il.Load(load_store_sz, ILREG_O(operand2)))));
break;
case MEM_OFFSET:
- if (!load_store_sz)
- load_store_sz = REGSZ_O(operand1);
+ if ((operand1.reg[0] >= REG_W0 && operand1.reg[0] <= REG_WSP) || (operand1.reg[0] >= REG_S0 && operand1.reg[0] <= REG_S31))
+ {
+ BNRegisterInfo regInfo = il.GetArchitecture()->GetRegisterInfo(operand1.reg[0]);
+ operand1.reg[0] = (Register)regInfo.fullWidthRegister;
+ }
// operand1.reg = [operand2.reg + operand2.imm]
if (IMM_O(operand2) == 0)
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Research direction
Start in arch/arm64/il.cpp at LoadStoreOperand and inspect how the AArch64 IL handles the 32-bit load into w17 followed by a jump through x17. Reproduce with the attached binary in Binja, navigate to strtoul in .plt, and confirm the 0x401dcc jump is translated with x17 as a resolved constant rather than an incorrect tag.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- reverse-engineering
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 45/100