Fix: NULL passed to memcpy in error path

CID 1378708:  Null pointer dereferences  (FORWARD_NULL)
Passing null pointer "data" to "memcpy", which dereferences it.

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

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index 5fd123cf0d855e66c3da6ea05fb06a58a6456631..96d0a180a27b079834bc0fb16c977e09ad1600a8 100644 (file)
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -1480,12 +1480,11 @@ static
 int viewer_get_packet(struct relay_connection *conn)
 {
        int ret;
-       char *data = NULL;
+       char *reply = NULL;
        struct lttng_viewer_get_packet get_packet_info;
-       struct lttng_viewer_trace_packet reply;
+       struct lttng_viewer_trace_packet reply_header;
        struct relay_viewer_stream *vstream = NULL;
-       bool skip_send_data = false;
-       uint32_t send_len = sizeof(reply);
+       uint32_t reply_size = sizeof(reply_header);
        uint32_t packet_data_len = 0;
        ssize_t read_len;
 
@@ -1501,29 +1500,26 @@ int viewer_get_packet(struct relay_connection *conn)
        health_code_update();
 
        /* From this point on, the error label can be reached. */
-       memset(&reply, 0, sizeof(reply));
+       memset(&reply_header, 0, sizeof(reply_header));
 
        vstream = viewer_stream_get_by_id(be64toh(get_packet_info.stream_id));
        if (!vstream) {
-               skip_send_data = true;
                DBG("Client requested packet of unknown stream id %" PRIu64,
                                be64toh(get_packet_info.stream_id));
-               reply.status = htobe32(LTTNG_VIEWER_GET_PACKET_ERR);
+               reply_header.status = htobe32(LTTNG_VIEWER_GET_PACKET_ERR);
+               goto send_reply_nolock;
        } else {
                packet_data_len = be32toh(get_packet_info.len);
-               send_len += packet_data_len;
+               reply_size += packet_data_len;
        }
 
-       data = zmalloc(send_len);
-       if (!data) {
-               PERROR("relay data zmalloc");
+       reply = zmalloc(reply_size);
+       if (!reply) {
+               PERROR("packet reply zmalloc");
+               reply_size = sizeof(reply_header);
                goto error;
        }
 
-       if (skip_send_data) {
-               goto send_reply_nolock;
-       }
-
        pthread_mutex_lock(&vstream->stream->lock);
        ret = lseek(vstream->stream_fd->fd, be64toh(get_packet_info.offset),
                        SEEK_SET);
@@ -1533,7 +1529,7 @@ int viewer_get_packet(struct relay_connection *conn)
                goto error;
        }
        read_len = lttng_read(vstream->stream_fd->fd,
-                       data + sizeof(reply),
+                       reply + sizeof(reply_header),
                        packet_data_len);
        if (read_len < packet_data_len) {
                PERROR("Relay reading trace file, fd: %d, offset: %" PRIu64,
@@ -1541,12 +1537,12 @@ int viewer_get_packet(struct relay_connection *conn)
                                be64toh(get_packet_info.offset));
                goto error;
        }
-       reply.status = htobe32(LTTNG_VIEWER_GET_PACKET_OK);
-       reply.len = htobe32(packet_data_len);
+       reply_header.status = htobe32(LTTNG_VIEWER_GET_PACKET_OK);
+       reply_header.len = htobe32(packet_data_len);
        goto send_reply;
 
 error:
-       reply.status = htobe32(LTTNG_VIEWER_GET_PACKET_ERR);
+       reply_header.status = htobe32(LTTNG_VIEWER_GET_PACKET_ERR);
 
 send_reply:
        if (vstream) {
@@ -1556,20 +1552,26 @@ send_reply_nolock:
 
        health_code_update();
 
-       memcpy(data, &reply, sizeof(reply));
-       health_code_update();
-       ret = send_response(conn->sock, data, send_len);
+       if (reply) {
+               memcpy(reply, &reply_header, sizeof(reply_header));
+               ret = send_response(conn->sock, reply, reply_size);
+       } else {
+               /* No reply to send. */
+               ret = send_response(conn->sock, &reply_header,
+                               reply_size);
+       }
+
        health_code_update();
        if (ret < 0) {
                PERROR("sendmsg of packet data failed");
                goto end_free;
        }
 
-       DBG("Sent %u bytes for stream %" PRIu64, send_len,
+       DBG("Sent %u bytes for stream %" PRIu64, reply_size,
                        be64toh(get_packet_info.stream_id));
 
 end_free:
-       free(data);
+       free(reply);
 end:
        if (vstream) {
                viewer_stream_put(vstream);