Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit afbe1a5b authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

bpf: remove never-hit branches in verifier adjust_scalar_min_max_vals 



In verifier function adjust_scalar_min_max_vals,
when src_known is false and the opcode is BPF_LSH/BPF_RSH,
early return will happen in the function. So remove
the branch in handling BPF_LSH/BPF_RSH when src_known is false.

Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 849fa506

kernel/bpf/verifier.c

+2 −9
Original line number Diff line number Diff line
@@ -2940,10 +2940,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, 
			dst_reg->umin_value <<= umin_val;

			dst_reg->umax_value <<= umax_val;

		}

		if (src_known)

		dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);

		else

			dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val);

		/* We may learn something more from the var_off */

		__update_reg_bounds(dst_reg);

		break;
@@ -2971,11 +2968,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, 
		 */

		dst_reg->smin_value = S64_MIN;

		dst_reg->smax_value = S64_MAX;

		if (src_known)

			dst_reg->var_off = tnum_rshift(dst_reg->var_off,

						       umin_val);

		else

			dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val);

		dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);

		dst_reg->umin_value >>= umax_val;

		dst_reg->umax_value >>= umin_val;

		/* We may learn something more from the var_off */