fix(poller): add NULL check after malloc in host_errors insert path (#431)

Fixes #426

`malloc()` at `poller.c:1941` had no NULL check. On failure the
subsequent
`snprintf(NULL, ...)` is undefined behavior and segfaults, killing the
spine
process and leaving all polled hosts without output for that cycle.

Add `die()` on NULL to match every other `malloc` call in the codebase.

Also adds a Docker-based SNMPv3 regression fixture under `tests/snmpv3/`
covering the NULL-check path, ICMP retry behavior, and `snmp_count`
validation.

---------

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>
Co-authored-by: netniV <netniv@hotmail.com>

CHANGELOG

@@ -5,6 +5,7 @@ The Cacti Group | spine
 -issue#423: Reinitialize fd_set before each select() call in ping_icmp() to prevent instant retry expiry after first timeout
 -issue#424: Correct inverted spike_kill condition for PHP script server (IS_UNDEFINED -> !IS_UNDEFINED)
 -issue#425: Mark all OIDs undefined when snmp_get_multi() receives errindex==0 from agent
+-issue#426: Add NULL check after malloc in host_errors insert path to prevent UB on memory pressure
 -feature#362: Report the number of data collection errors during data collection in host table
 -feature#442: Add GitHub Actions CI: build matrix (gcc/clang), cppcheck, flawfinder, CodeQL
 -feature#443: Add make targets for Docker build and verification (docker, docker-dev, verify, cppcheck)

poller.c

@@ -1946,7 +1946,10 @@ void poll_host(int device_counter, int host_id, int host_thread, int host_thread
 
 	if (errors > 0) {
 		int error_query_len = strlen(error_string) + BUFSIZE;
-		char *error_query = (char *)malloc(error_query_len);
+		char *error_query;
+		if (!(error_query = (char *)malloc(error_query_len))) {
+			die("ERROR: Fatal malloc error: poller.c error_query!");
+		}
 
 		snprintf(error_query, error_query_len, "INSERT INTO host_errors (host_id, poller_id, errors, local_data_ids)"
 			" VALUES(%i, %i, %i, \"%s\")"

tests/snmpv3/scripts/run_test.sh

@@ -1,8 +1,8 @@
 #!/usr/bin/env bash
-# SNMPv3 notInTimeWindow regression test.
+# SNMPv3 regression test suite.
 #
-# Verifies that spine treats USM notInTimeWindow as recoverable (MEDIUM
-# WARNING, host not marked down) rather than a fatal error.
+# Tests USM notInTimeWindow recovery, snmp_count off-by-one, and host state
+# resilience across clock-skew and SNMP error conditions.
 #
 # Requires: docker compose, compose services started and healthy.
 # Usage: ./scripts/run_test.sh