Re: [PATCH v2] seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()

[Steven Rostedt]

On Thu, 26 Oct 2023 12:40:37 -0700
Kees Cook <keescook@xxxxxxxxxxxx> wrote:

> @@ -81,16 +88,20 @@ static inline unsigned int seq_buf_used(struct seq_buf *s)
>   *
>   * After this function is called, s->buffer is safe to use
>   * in string operations.
> + *
> + * Returns @s->buf after making sure it is terminated.
>   */
> -static inline void seq_buf_terminate(struct seq_buf *s)
> +static inline char *seq_buf_str(struct seq_buf *s)

Looking at show_buffer() (below), I wonder if this should be:

static inline const char *seq_buf_str() ?

I mean, it can be modified, but do we want to allow that?

-- Steve


>  {
>  	if (WARN_ON(s->size == 0))
> -		return;
> +		return "";
>  
>  	if (seq_buf_buffer_left(s))
>  		s->buffer[s->len] = 0;
>  	else
>  		s->buffer[s->size - 1] = 0;
> +
> +	return s->buffer;
>  }
>  
>  /**
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index d629065c2383..2539cfc20a97 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3828,15 +3828,6 @@ static bool trace_safe_str(struct trace_iterator *iter, const char *str,
>  	return false;
>  }
>  
> -static const char *show_buffer(struct trace_seq *s)
> -{
> -	struct seq_buf *seq = &s->seq;
> -
> -	seq_buf_terminate(seq);
> -
> -	return seq->buffer;
> -}
> -
>  static DEFINE_STATIC_KEY_FALSE(trace_no_verify);
>