Re: [PATCH bpf-next v3 1/6] bpf/verifier: replace calls to mark_reg_unknown.

[Eduard Zingerman <eddyz87@gmail.com>]

On Wed, 2024-04-24 at 23:40 +0100, Cupertino Miranda wrote:
> In order to further simplify the code in adjust_scalar_min_max_vals all
> the calls to mark_reg_unknown are replaced by __mark_reg_unknown.
> 
> Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
> Cc: Yonghong Song <yonghong.song@linux.dev>
> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Cc: David Faust <david.faust@oracle.com>
> Cc: Jose Marchesi <jose.marchesi@oracle.com>
> Cc: Elena Zannoni <elena.zannoni@oracle.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

Nit: if there would be a v4 for this series (hopefully won't),
     please extend the commit message with something like below:
     
  static void mark_reg_unknown(struct bpf_verifier_env *env,
  			     struct bpf_reg_state *regs, u32 regno)
  {
  	if (WARN_ON(regno >= MAX_BPF_REG)) {
  		... mark all regs not init ...
  		return;
      }
  	__mark_reg_unknown(env, regs + regno);
  }
  
  The 'regno >= MAX_BPF_REG' does not apply to adjust_scalar_min_max_vals(),
  because it is only called from the following stack:
  - check_alu_op
    - adjust_reg_min_max_vals
      - adjust_scalar_min_max_vals
  
  The check_alu_op() does check_reg_arg() which verifies that both src
  and dst register numbers are within bounds.

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