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Fix eBPF lddw opcode #1885

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merged 1 commit into from
Jun 9, 2022
Merged

Fix eBPF lddw opcode #1885

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7 changes: 4 additions & 3 deletions arch/BPF/BPFDisassembler.c
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,8 @@ static bpf_internal* fetch_ebpf(cs_struct *ud, const uint8_t *code,
return NULL;

bpf->op = (uint16_t)code[0];
bpf->dst = code[1] & 0xf;
bpf->src = (code[1] & 0xf0) >> 4;

// eBPF has one 16-byte instruction: BPF_LD | BPF_DW | BPF_IMM,
// in this case imm is combined with the next block's imm.
Expand All @@ -82,8 +84,6 @@ static bpf_internal* fetch_ebpf(cs_struct *ud, const uint8_t *code,
bpf->insn_size = 16;
}
else {
bpf->dst = code[1] & 0xf;
bpf->src = (code[1] & 0xf0) >> 4;
bpf->offset = read_u16(ud, code + 2);
bpf->k = read_u32(ud, code + 4);
}
Expand Down Expand Up @@ -178,7 +178,7 @@ static bool decodeLoad(cs_struct *ud, MCInst *MI, bpf_internal *bpf)

/* eBPF mode */
/*
* - IMM: lddw imm64
* - IMM: lddw dst, imm64
* - ABS: ld{w,h,b,dw} [k]
* - IND: ld{w,h,b,dw} [src+k]
* - MEM: ldx{w,h,b,dw} dst, [src+off]
Expand All @@ -188,6 +188,7 @@ static bool decodeLoad(cs_struct *ud, MCInst *MI, bpf_internal *bpf)
case BPF_MODE_IMM:
if (bpf->op != (BPF_CLASS_LD | BPF_SIZE_DW | BPF_MODE_IMM))
return false;
CHECK_WRITABLE_AND_PUSH(ud, MI, bpf->dst);
MCOperand_CreateImm0(MI, bpf->k);
return true;
case BPF_MODE_ABS:
Expand Down
7 changes: 6 additions & 1 deletion arch/BPF/BPFInstPrinter.c
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Expand Up @@ -83,7 +83,12 @@ static void convert_operands(MCInst *MI, cs_bpf *bpf)
if (BPF_CLASS(opcode) == BPF_CLASS_LD || BPF_CLASS(opcode) == BPF_CLASS_LDX) {
switch (BPF_MODE(opcode)) {
case BPF_MODE_IMM:
push_op_imm(bpf, MCOperand_getImm(MCInst_getOperand(MI, 0)));
if (EBPF_MODE(MI->csh)) {
push_op_reg(bpf, MCOperand_getReg(MCInst_getOperand(MI, 0)), CS_AC_WRITE);
push_op_imm(bpf, MCOperand_getImm(MCInst_getOperand(MI, 1)));
} else {
push_op_imm(bpf, MCOperand_getImm(MCInst_getOperand(MI, 0)));
}
break;
case BPF_MODE_ABS:
op = MCInst_getOperand(MI, 0);
Expand Down
6 changes: 4 additions & 2 deletions arch/BPF/BPFMapping.c
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Expand Up @@ -292,7 +292,7 @@ static void update_regs_access(cs_struct *ud, cs_detail *detail,
} while (0)
/*
* In eBPF mode, only these instructions have implicit registers access:
* - ld{w,h,b,dw} * // w: r0
* - legacy ld{w,h,b,dw} * // w: r0
* - exit // r: r0
*/
if (EBPF_MODE(ud)) {
Expand All @@ -303,7 +303,9 @@ static void update_regs_access(cs_struct *ud, cs_detail *detail,
case BPF_INS_LDH:
case BPF_INS_LDB:
case BPF_INS_LDDW:
PUSH_WRITE(BPF_REG_R0);
if (BPF_MODE(opcode) == BPF_MODE_ABS || BPF_MODE(opcode) == BPF_MODE_IND) {
PUSH_WRITE(BPF_REG_R0);
}
break;
case BPF_INS_EXIT:
PUSH_READ(BPF_REG_R0);
Expand Down
2 changes: 1 addition & 1 deletion suite/MC/BPF/extended-all.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@
0x14,0xd9,0xba,0xb8,0x6f,0x07,0x93,0x2a = sub r9, 0x2a93076f
0x15,0x6a,0x9f,0x38,0x1a,0x9d,0xb7,0x4d = jeq r10, 0x4db79d1a, +0x389f
0x17,0xc5,0x60,0xed,0x0b,0xdc,0xe6,0x22 = sub64 r5, 0x22e6dc0b
0x18,0xa3,0x5c,0x14,0xde,0xf0,0xa5,0xff,0x9a,0x7e,0x10,0xee,0xd8,0xa4,0x2b,0x2f = lddw 0x2f2ba4d8ffa5f0de
0x18,0xa3,0x5c,0x14,0xde,0xf0,0xa5,0xff,0x9a,0x7e,0x10,0xee,0xd8,0xa4,0x2b,0x2f = lddw r3, 0x2f2ba4d8ffa5f0de
0x1c,0x73,0x68,0xa4,0x8b,0x5b,0x93,0x1f = sub r3, r7
0x1d,0x21,0x20,0x4d,0xe3,0x47,0xaf,0x1b = jeq r1, r2, +0x4d20
0x1f,0x06,0x51,0x5a,0x39,0xb2,0x10,0x10 = sub64 r6, r0
Expand Down
2 changes: 1 addition & 1 deletion suite/MC/BPF/extended-be.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@
0x30,0x00,0x00,0x00,0x00,0x00,0x00,0x00 = ldb [0x0]
0x28,0x00,0x00,0x00,0xfa,0x00,0x00,0xff = ldh [0xfa0000ff]
0x40,0x10,0x00,0x00,0xcc,0x00,0x00,0x00 = ldw [r1+0xcc000000]
0x18,0x00,0x00,0x00,0x0c,0xb0,0xce,0xfa,0x00,0x00,0x00,0x00,0xef,0xbe,0xad,0xde = lddw 0xefbeadde0cb0cefa
0x18,0x00,0x00,0x00,0x0c,0xb0,0xce,0xfa,0x00,0x00,0x00,0x00,0xef,0xbe,0xad,0xde = lddw r0, 0xefbeadde0cb0cefa
0x71,0x13,0x11,0x00,0x00,0x00,0x00,0x00 = ldxb r3, [r1+0x1100]
0x94,0x09,0x00,0x00,0x37,0x13,0x03,0x00 = mod r9, 0x37130300
0x84,0x03,0x00,0x00,0x00,0x00,0x00,0x00 = neg r3
Expand Down