From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Sat, 14 Sep 2019 20:16:56 +0000 (-0400)
Subject: sessiond: fix: possible unaligned access in packed structure
X-Git-Tag: v2.12.0-rc1~382
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=a914e76ac1a529191035f1fec439026c83beee3f

sessiond: fix: possible unaligned access in packed structure

Use a temporary snapshot_id in cmd_rotate_get_info() to obtain the
return value of cmd_snapshot_add_output() and explicitly assign it to
the reply communication structure. Otherwise, &reply.id may be
unaligned.

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

diff --git a/src/bin/lttng-sessiond/client.c b/src/bin/lttng-sessiond/client.c
index 7b7642ea7..fa7672b58 100644
--- a/src/bin/lttng-sessiond/client.c
+++ b/src/bin/lttng-sessiond/client.c
@@ -1712,13 +1712,15 @@ error_add_context:
 	}
 	case LTTNG_SNAPSHOT_ADD_OUTPUT:
 	{
+		uint32_t snapshot_id;
 		struct lttcomm_lttng_output_id reply;
 
 		ret = cmd_snapshot_add_output(cmd_ctx->session,
-				&cmd_ctx->lsm->u.snapshot_output.output, &reply.id);
+				&cmd_ctx->lsm->u.snapshot_output.output, &snapshot_id);
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
+		reply.id = snapshot_id;
 
 		ret = setup_lttng_msg_no_cmd_header(cmd_ctx, &reply,
 			sizeof(reply));