On Sat, Feb 04, 2017 at 08:37:29AM -0800, William Tu wrote:
> The patch fixes the case when adding a zero value to the packet
> pointer. The zero value could come from src_reg equals type
> BPF_K or CONST_IMM. The patch fixes both, otherwise the verifer
> reports the following error:
> [...]
> R0=imm0,min_value=0,max_value=0
> R1=pkt(id=0,off=0,r=4)
> R2=pkt_end R3=fp-12
> R4=imm4,min_value=4,max_value=4
> R5=pkt(id=0,off=4,r=4)
> 269: (bf) r2 = r0 // r2 becomes imm0
> 270: (77) r2 >>= 3
> 271: (bf) r4 = r1 // r4 becomes pkt ptr
> 272: (0f) r4 += r2 // r4 += 0
> addition of negative constant to packet pointer is not allowed
>
> Signed-off-by: William Tu <u9012...@gmail.com>
> Signed-off-by: Mihai Budiu <mbu...@vmware.com>
> Cc: Daniel Borkmann <dan...@iogearbox.net>
> Cc: Alexei Starovoitov <a...@kernel.org>
> Acked-by: Daniel Borkmann <dan...@iogearbox.net>
...
> + "direct packet access: test14 (pkt_ptr += 0, CONST_IMM, good
> access)",
> + .insns = {
> + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
> + offsetof(struct __sk_buff, data)),
> + BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
> + offsetof(struct __sk_buff, data_end)),
> + BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 22),
> + BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 7),
> + BPF_MOV64_IMM(BPF_REG_5, 12),
> + BPF_ALU64_IMM(BPF_RSH, BPF_REG_5, 4),
> + BPF_MOV64_REG(BPF_REG_6, BPF_REG_2),
> + BPF_ALU64_REG(BPF_ADD, BPF_REG_6, BPF_REG_5),
> + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6, 0),
Now looks great. Thanks!
Acked-by: Alexei Starovoitov <a...@kernel.org>
