From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Wed, 11 Sep 2019 16:03:38 +0000 (-0400)
Subject: relayd: fix: rotate_truncate_stream() assumes non-null next chunk
X-Git-Tag: v2.12.0-rc1~402
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=4147107d9646011a1cdb7166a9810065927af99c

relayd: fix: rotate_truncate_stream() assumes non-null next chunk

While the protocol doesn't allow a stream rotation position in the
past when rotating to a "NULL" trace chunk, a misbehaving peer could
express this. Report the protocol error and abort the truncation
operation in this case.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-relayd/stream.c b/src/bin/lttng-relayd/stream.c
index f98b46557..06e82b291 100644
--- a/src/bin/lttng-relayd/stream.c
+++ b/src/bin/lttng-relayd/stream.c
@@ -210,6 +210,16 @@ static int rotate_truncate_stream(struct relay_stream *stream)
 	struct stream_fd *previous_stream_fd = NULL;
 	struct lttng_trace_chunk *previous_chunk = NULL;
 
+	if (!LTTNG_OPTIONAL_GET(&stream->ongoing_rotation)->next_trace_chunk) {
+		ERR("Protocol error encoutered in %s(): stream rotation "
+			"sequence number is before the current sequence number "
+			"and the next trace chunk is unset. Honoring this "
+			"rotation command would result in data loss",
+				__FUNCTION__);
+		ret = -1;
+		goto end;
+	}
+
 	ASSERT_LOCKED(stream->lock);
 	/*
 	 * Acquire a reference to the current trace chunk to ensure
@@ -245,6 +255,7 @@ static int rotate_truncate_stream(struct relay_stream *stream)
 		goto end;
 	}
 
+	assert(stream->stream_fd);
 	/*
 	 * Seek the current tracefile to the position at which the rotation
 	 * should have occurred.