bpf: remove never-hit branches in verifier adjust_scalar_min_max_vals (afbe1a5b) · Commits · 戴 / test

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:

Alexei Starovoitov <ast@kernel.org> Signed-off-by:

Yonghong Song <yhs@fb.com> Signed-off-by:

Alexei Starovoitov <ast@kernel.org>

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 */

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