Fix nullness check to src value in MOD32 and DIV32

Signed-off-by: Richard Smith <ret2happy@126.com>

src/interpreter.rs

@@ -216,9 +216,9 @@ pub fn execute_program(prog_: Option<&[u8]>, mem: &[u8], mbuff: &[u8], helpers:
             ebpf::SUB32_REG  => reg[_dst] = (reg[_dst] as i32).wrapping_sub(reg[_src] as i32) as u64,
             ebpf::MUL32_IMM  => reg[_dst] = (reg[_dst] as i32).wrapping_mul(insn.imm)         as u64,
             ebpf::MUL32_REG  => reg[_dst] = (reg[_dst] as i32).wrapping_mul(reg[_src] as i32) as u64,
-            ebpf::DIV32_IMM if insn.imm == 0 => reg[_dst] = 0,
+            ebpf::DIV32_IMM if insn.imm as u32 == 0 => reg[_dst] = 0,
             ebpf::DIV32_IMM  => reg[_dst] = (reg[_dst] as u32 / insn.imm              as u32) as u64,
-            ebpf::DIV32_REG if reg[_src] == 0 => reg[_dst] = 0,
+            ebpf::DIV32_REG if reg[_src] as u32 == 0 => reg[_dst] = 0,
             ebpf::DIV32_REG  => reg[_dst] = (reg[_dst] as u32 / reg[_src]             as u32) as u64,
             ebpf::OR32_IMM   =>   reg[_dst] = (reg[_dst] as u32             | insn.imm  as u32) as u64,
             ebpf::OR32_REG   =>   reg[_dst] = (reg[_dst] as u32             | reg[_src] as u32) as u64,
@@ -229,9 +229,9 @@ pub fn execute_program(prog_: Option<&[u8]>, mem: &[u8], mbuff: &[u8], helpers:
             ebpf::RSH32_IMM  =>   reg[_dst] = (reg[_dst] as u32).wrapping_shr(insn.imm  as u32) as u64,
             ebpf::RSH32_REG  =>   reg[_dst] = (reg[_dst] as u32).wrapping_shr(reg[_src] as u32) as u64,
             ebpf::NEG32      => { reg[_dst] = (reg[_dst] as i32).wrapping_neg()                 as u64; reg[_dst] &= U32MAX; },
-            ebpf::MOD32_IMM if insn.imm == 0 => (),
+            ebpf::MOD32_IMM if insn.imm as u32 == 0 => (),
             ebpf::MOD32_IMM  =>   reg[_dst] = (reg[_dst] as u32             % insn.imm  as u32) as u64,
-            ebpf::MOD32_REG if reg[_src] == 0 => (),
+            ebpf::MOD32_REG if reg[_src] as u32 == 0 => (),
             ebpf::MOD32_REG  =>   reg[_dst] = (reg[_dst] as u32 % reg[_src]             as u32) as u64,
             ebpf::XOR32_IMM  =>   reg[_dst] = (reg[_dst] as u32             ^ insn.imm  as u32) as u64,
             ebpf::XOR32_REG  =>   reg[_dst] = (reg[_dst] as u32             ^ reg[_src] as u32) as u64,