Re: [PATCH v2 1/5] telemetry: fix autotest failures on Alpine

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Wed, Apr 05, 2023 at 04:44:10PM +0100, Bruce Richardson wrote:
> On Alpine linux, the telemetry_data_autotest was failing for the
> test where we had dictionaries embedded in other dictionaries up
> to three levels deep. Indications are that this issue is due to
> excess data being stored on the stack, so replace stack-allocated
> buffer data with dynamically allocated data in the case where we
> are doing recursive processing of telemetry data structures into
> json.
> 
> Bugzilla ID: 1177
> Fixes: c933bb5177ca ("telemetry: support array values in data object")
> Fixes: d2671e642a8e ("telemetry: support dict of dicts")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> 
> ---
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

(one observation below)

> V2:
>   set '\0' in newly malloc'ed buffer to ensure it always has valid
>   string data.
> ---
>  lib/telemetry/telemetry.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/telemetry/telemetry.c b/lib/telemetry/telemetry.c
> index 7bceadcee7..728a0bffd4 100644
> --- a/lib/telemetry/telemetry.c
> +++ b/lib/telemetry/telemetry.c
> @@ -208,7 +208,11 @@ container_to_json(const struct rte_tel_data *d, char *out_buf, size_t buf_len)
>  				break;
>  			case RTE_TEL_CONTAINER:
>  			{
> -				char temp[buf_len];
> +				char *temp = malloc(buf_len);
> +				if (temp == NULL)
> +					break;
> +				*temp = '\0';  /* ensure valid string */
> +
>  				const struct container *cont =
>  						&v->value.container;
>  				if (container_to_json(cont->data,
> @@ -219,6 +223,7 @@ container_to_json(const struct rte_tel_data *d, char *out_buf, size_t buf_len)
>  							v->name, temp);
>  				if (!cont->keep)
>  					rte_tel_data_free(cont->data);
> +				free(temp);
>  				break;
>  			}
>  			}
> @@ -275,7 +280,11 @@ output_json(const char *cmd, const struct rte_tel_data *d, int s)
>  				break;
>  			case RTE_TEL_CONTAINER:
>  			{
> -				char temp[buf_len];
> +				char *temp = malloc(buf_len);
> +				if (temp == NULL)
> +					break;
> +				*temp = '\0';  /* ensure valid string */
> +
>  				const struct container *cont =
>  						&v->value.container;
>  				if (container_to_json(cont->data,
> @@ -286,6 +295,7 @@ output_json(const char *cmd, const struct rte_tel_data *d, int s)
>  							v->name, temp);
>  				if (!cont->keep)
>  					rte_tel_data_free(cont->data);
> +				free(temp);

not expressing a preference just noticing that when
RTE_TEL_CONTAINER cases are the last case in the switch sometimes there
is an explicit break; and sometimes not.

>  			}
>  			}
>  		}
> @@ -311,7 +321,11 @@ output_json(const char *cmd, const struct rte_tel_data *d, int s)
>  						buf_len, used,
>  						d->data.array[i].uval);
>  			else if (d->type == TEL_ARRAY_CONTAINER) {
> -				char temp[buf_len];
> +				char *temp = malloc(buf_len);
> +				if (temp == NULL)
> +					break;
> +				*temp = '\0';  /* ensure valid string */
> +
>  				const struct container *rec_data =
>  						&d->data.array[i].container;
>  				if (container_to_json(rec_data->data,
> @@ -321,6 +335,7 @@ output_json(const char *cmd, const struct rte_tel_data *d, int s)
>  							buf_len, used, temp);
>  				if (!rec_data->keep)
>  					rte_tel_data_free(rec_data->data);
> +				free(temp);
>  			}
>  		break;
>  	}
> -- 
> 2.37.2