4.2.8-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Zi Shen Lim <zlim.lnx@xxxxxxxxx> commit 14e589ff4aa3f28a5424e92b6495ecb8950080f7 upstream. Turns out in the case of modulo by zero in a BPF program: A = A % X; (X == 0) the expected behavior is to terminate with return value 0. The bug in JIT is exposed by a new test case [1]. [1] https://lkml.org/lkml/2015/11/4/499 Signed-off-by: Zi Shen Lim <zlim.lnx@xxxxxxxxx> Reported-by: Yang Shi <yang.shi@xxxxxxxxxx> Reported-by: Xi Wang <xi.wang@xxxxxxxxx> CC: Alexei Starovoitov <ast@xxxxxxxxxxxx> Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx> --- arch/arm64/net/bpf_jit_comp.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 9ae6f23..6217f80 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -269,6 +269,8 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) break; case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: + case BPF_ALU | BPF_MOD | BPF_X: + case BPF_ALU64 | BPF_MOD | BPF_X: { const u8 r0 = bpf2a64[BPF_REG_0]; @@ -281,16 +283,19 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) check_imm26(jmp_offset); emit(A64_B(jmp_offset), ctx); /* else */ - emit(A64_UDIV(is64, dst, dst, src), ctx); + switch (BPF_OP(code)) { + case BPF_DIV: + emit(A64_UDIV(is64, dst, dst, src), ctx); + break; + case BPF_MOD: + ctx->tmp_used = 1; + emit(A64_UDIV(is64, tmp, dst, src), ctx); + emit(A64_MUL(is64, tmp, tmp, src), ctx); + emit(A64_SUB(is64, dst, dst, tmp), ctx); + break; + } break; } - case BPF_ALU | BPF_MOD | BPF_X: - case BPF_ALU64 | BPF_MOD | BPF_X: - ctx->tmp_used = 1; - emit(A64_UDIV(is64, tmp, dst, src), ctx); - emit(A64_MUL(is64, tmp, tmp, src), ctx); - emit(A64_SUB(is64, dst, dst, tmp), ctx); - break; case BPF_ALU | BPF_LSH | BPF_X: case BPF_ALU64 | BPF_LSH | BPF_X: emit(A64_LSLV(is64, dst, dst, src), ctx); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html