commit 1bbaa929b77113532785c408dd1b41cd0521ffc8
Author: Chrissie Caulfield <ccaulfie@redhat.com>
Date:   Thu Jul 20 07:19:01 2023 +0100

    log: fix potential overflow with long log messages (#490)
    
    qb_vsnprintf_serialize was called with 'max_size' as the
    limiting number for the length of the formatted log
    message. But the buffer also needs to contain the
    log header (given by 'actual_size'), so we now pass
    't->max_line_length' as the maximum length of the
    formatted log message to limit space to the actual
    bytes left
    
    Also added error checks to the blackbox calls at
    the end of the test, as these now provide a proper
    test that the BB is functioning. Before they were
    masking failures.

diff --git a/lib/log_blackbox.c b/lib/log_blackbox.c
index 3e30504..8519a48 100644
--- a/lib/log_blackbox.c
+++ b/lib/log_blackbox.c
@@ -110,8 +110,8 @@ _blackbox_vlogger(int32_t target,
 	chunk += sizeof(uint32_t);
 
 	/* log message */
-	msg_len = qb_vsnprintf_serialize(chunk, max_size, cs->format, ap);
-	if (msg_len >= max_size) {
+	msg_len = qb_vsnprintf_serialize(chunk, t->max_line_length, cs->format, ap);
+	if (msg_len >= t->max_line_length) {
 	    chunk = msg_len_pt + sizeof(uint32_t); /* Reset */
 
 	    /* Leave this at QB_LOG_MAX_LEN so as not to overflow the blackbox */
diff --git a/tests/check_log.c b/tests/check_log.c
index 039a4bb..e5abf40 100644
--- a/tests/check_log.c
+++ b/tests/check_log.c
@@ -832,8 +832,10 @@ START_TEST(test_log_long_msg)
 		qb_log(LOG_INFO, "Message %d %d - %s", lpc, lpc%600, buffer);
 	}
 
-        qb_log_blackbox_write_to_file("blackbox.dump");
-        qb_log_blackbox_print_from_file("blackbox.dump");
+        rc = qb_log_blackbox_write_to_file("blackbox.dump");
+	ck_assert_int_gt(rc, 0);
+        rc = qb_log_blackbox_print_from_file("blackbox.dump");
+	ck_assert_int_le(rc, 0);
 	unlink("blackbox.dump");
 	qb_log_fini();
 }