bpf: reset id on CONST_IMM transition

Whenever we set the register to the type CONST_IMM, we currently don't
reset the id to 0. id member is not used in CONST_IMM case, so don't
let it become stale, where pruning won't be able to match later on.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d031b3b0752ea00e8e8d93106b68ab5226b0a65e..d195d825515aac119f5c13637cabe41d3b25a26d 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1952,6 +1952,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
                         */
                        regs[insn->dst_reg].type = CONST_IMM;
                        regs[insn->dst_reg].imm = insn->imm;
+                       regs[insn->dst_reg].id = 0;
                        regs[insn->dst_reg].max_value = insn->imm;
                        regs[insn->dst_reg].min_value = insn->imm;
                        regs[insn->dst_reg].min_align = calc_align(insn->imm);
@@ -2409,6 +2410,7 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 
                regs[insn->dst_reg].type = CONST_IMM;
                regs[insn->dst_reg].imm = imm;
+               regs[insn->dst_reg].id = 0;
                return 0;
        }