[PATCH v3 1/5] telemetry: fix autotest failures on Alpine

[Bruce Richardson <bruce.richardson@intel.com>]

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(-)

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);
 			}
 			}
 		}
@@ -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