[CritFix] - Fix reported length of logging structure

The logging code contains one place where the apparent size of the
logging structure is defined and then it's actually utilized in another
place. Re-writes and refactoring this code ended up with these
values to not co-relate what was previously there resulting in a stack
overwrite in last version or currently in log truncation.

Move assignment of logging structure to the place where it's actually
used, reducing future logic de-sync dangers. Also move the g_assert() to
the end as it should be a development aid only.

1 files changed, 11 insertions, 31 deletions

diff --git a/src/libserver/logger/logger.c b/src/libserver/logger/logger.c
index e10dfd392..2dae6329b 100644
--- a/src/libserver/logger/logger.c
+++ b/src/libserver/logger/logger.c
@@ -1052,37 +1052,6 @@ void rspamd_log_fill_iov(struct rspamd_logger_iov_ctx *iov_ctx,
 	}
 
 	glong r;
-
-	if (iov_ctx->niov == 0) {
-		/* This is the case when we just return a number of IOV required for the logging */
-		if (log_json) {
-			iov_ctx->niov = 3; /* Preamble, message, "}\n" */
-		}
-		else {
-			if (log_rspamadm) {
-				if (logger->log_level == G_LOG_LEVEL_DEBUG) {
-					iov_ctx->niov = 4;
-				}
-				else {
-					iov_ctx->niov = 3; /* No time component */
-				}
-			}
-			else if (log_systemd) {
-				iov_ctx->niov = 3;
-			}
-			else {
-				if (log_color) {
-					iov_ctx->niov = 5;
-				}
-				else {
-					iov_ctx->niov = 4;
-				}
-			}
-		}
-
-		g_assert(iov_ctx->niov <= G_N_ELEMENTS(iov_ctx->iov));
-	}
-
 	static gchar timebuf[64], modulebuf[64];
 	static gchar tmpbuf[256];
 
@@ -1208,6 +1177,8 @@ void rspamd_log_fill_iov(struct rspamd_logger_iov_ctx *iov_ctx,
 		}
 		iov_ctx->iov[2].iov_base = (void *) "\"}\n";
 		iov_ctx->iov[2].iov_len = sizeof("\"}\n") - 1;
+
+		iov_ctx->niov = 3;
 	}
 	else if (G_LIKELY(!log_rspamadm)) {
 		if (!log_systemd) {
@@ -1304,9 +1275,13 @@ void rspamd_log_fill_iov(struct rspamd_logger_iov_ctx *iov_ctx,
 		iov_ctx->iov[3].iov_base = (void *) &lf_chr;
 		iov_ctx->iov[3].iov_len = 1;
 
+		iov_ctx->niov = 4;
+
 		if (log_color) {
 			iov_ctx->iov[4].iov_base = "\033[0m";
 			iov_ctx->iov[4].iov_len = sizeof("\033[0m") - 1;
+
+			iov_ctx->niov = 5;
 		}
 	}
 	else {
@@ -1324,7 +1299,12 @@ void rspamd_log_fill_iov(struct rspamd_logger_iov_ctx *iov_ctx,
 		iov_ctx->iov[niov++].iov_len = mlen;
 		iov_ctx->iov[niov].iov_base = (void *) &lf_chr;
 		iov_ctx->iov[niov++].iov_len = 1;
+
+		iov_ctx->niov = niov;
 	}
+
+	// this is kind of "after-the-fact" check, but it's mostly for debugging-only
+	g_assert(iov_ctx->niov <= G_N_ELEMENTS(iov_ctx->iov));
 }
 
 void rspamd_log_iov_free(struct rspamd_logger_iov_ctx *iov_ctx)