From d9f484bc6f074842bc4ac3eab0127fe3aaa10909 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Wed, 29 Aug 2018 17:06:48 -0400
Subject: [PATCH] Fix: possible null dereference on communication error
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lttng_ctl_ask_sessiond_fds_varlen() can return a positive
error code and NULL buffers if the sessiond uses a command
return code that is already negative.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/lib/lttng-ctl/lttng-ctl.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index eff08df80..f503fd1cb 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -1959,6 +1959,11 @@ int lttng_list_events(struct lttng_handle *handle,
 		goto end;
 	}
 
+	if (!cmd_header) {
+		ret = -LTTNG_ERR_UNK;
+		goto end;
+	}
+
 	/* Set number of events and free command header */
 	nb_events = cmd_header->nb_events;
 	if (nb_events > INT_MAX) {
-- 
2.34.1