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

  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>

---
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(-)
  

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
  

On Fri, Apr 07, 2023 at 12:21:16PM -0700, Tyler Retzlaff wrote:
> 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.
> > ---
<snip>
> > @@ -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.
> 
I won't do a new patch revision just for that, but if I end up doing one
for other reasons I'll try and remember to make it more consistent.

thanks,
/Bruce