consumer: fix: unaligned accesses to index fields

The ctf_index structure, being part of the ABI, is explicitly packed
using the LTTNG_PACKED macro. However, populating it by using pointers
to its members is not acceptable as it may cause the ust and kernel
tracer APIs to populate write their return values using unaligned
pointers.

Use automatic storage variables to fetch the various index fields and
populate the index at-once using a compound literal.

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

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 29a27134f0e372c8c8295114048537a07dcc6453..aea1b4831d158da0052d0533d1dc9279096a1eca 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -1327,66 +1327,62 @@ end:
 static int get_index_values(struct ctf_packet_index *index, int infd)
 {
        int ret;
+       uint64_t packet_size, content_size, timestamp_begin, timestamp_end,
+                       events_discarded, stream_id, stream_instance_id,
+                       packet_seq_num;
 
-       ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
+       ret = kernctl_get_timestamp_begin(infd, &timestamp_begin);
        if (ret < 0) {
                PERROR("kernctl_get_timestamp_begin");
                goto error;
        }
-       index->timestamp_begin = htobe64(index->timestamp_begin);
 
-       ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
+       ret = kernctl_get_timestamp_end(infd, &timestamp_end);
        if (ret < 0) {
                PERROR("kernctl_get_timestamp_end");
                goto error;
        }
-       index->timestamp_end = htobe64(index->timestamp_end);
 
-       ret = kernctl_get_events_discarded(infd, &index->events_discarded);
+       ret = kernctl_get_events_discarded(infd, &events_discarded);
        if (ret < 0) {
                PERROR("kernctl_get_events_discarded");
                goto error;
        }
-       index->events_discarded = htobe64(index->events_discarded);
 
-       ret = kernctl_get_content_size(infd, &index->content_size);
+       ret = kernctl_get_content_size(infd, &content_size);
        if (ret < 0) {
                PERROR("kernctl_get_content_size");
                goto error;
        }
-       index->content_size = htobe64(index->content_size);
 
-       ret = kernctl_get_packet_size(infd, &index->packet_size);
+       ret = kernctl_get_packet_size(infd, &packet_size);
        if (ret < 0) {
                PERROR("kernctl_get_packet_size");
                goto error;
        }
-       index->packet_size = htobe64(index->packet_size);
 
-       ret = kernctl_get_stream_id(infd, &index->stream_id);
+       ret = kernctl_get_stream_id(infd, &stream_id);
        if (ret < 0) {
                PERROR("kernctl_get_stream_id");
                goto error;
        }
-       index->stream_id = htobe64(index->stream_id);
 
-       ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
+       ret = kernctl_get_instance_id(infd, &stream_instance_id);
        if (ret < 0) {
                if (ret == -ENOTTY) {
                        /* Command not implemented by lttng-modules. */
-                       index->stream_instance_id = -1ULL;
+                       stream_instance_id = -1ULL;
                } else {
                        PERROR("kernctl_get_instance_id");
                        goto error;
                }
        }
-       index->stream_instance_id = htobe64(index->stream_instance_id);
 
-       ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
+       ret = kernctl_get_sequence_number(infd, &packet_seq_num);
        if (ret < 0) {
                if (ret == -ENOTTY) {
                        /* Command not implemented by lttng-modules. */
-                       index->packet_seq_num = -1ULL;
+                       packet_seq_num = -1ULL;
                        ret = 0;
                } else {
                        PERROR("kernctl_get_sequence_number");
@@ -1395,6 +1391,18 @@ static int get_index_values(struct ctf_packet_index *index, int infd)
        }
        index->packet_seq_num = htobe64(index->packet_seq_num);
 
+       *index = (typeof(*index)) {
+               .offset = index->offset,
+               .packet_size = htobe64(packet_size),
+               .content_size = htobe64(content_size),
+               .timestamp_begin = htobe64(timestamp_begin),
+               .timestamp_end = htobe64(timestamp_end),
+               .events_discarded = htobe64(events_discarded),
+               .stream_id = htobe64(stream_id),
+               .stream_instance_id = htobe64(stream_instance_id),
+               .packet_seq_num = htobe64(packet_seq_num),
+       };
+
 error:
        return ret;
 }

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index 514278d91fd930fac88603286e93fec16c7691a5..b64ad04aaa3cd101b3275181b5b382a40fb62385 100644 (file)
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -2424,62 +2424,69 @@ static int get_index_values(struct ctf_packet_index *index,
                struct ustctl_consumer_stream *ustream)
 {
        int ret;
+       uint64_t packet_size, content_size, timestamp_begin, timestamp_end,
+                       events_discarded, stream_id, stream_instance_id,
+                       packet_seq_num;
 
-       ret = ustctl_get_timestamp_begin(ustream, &index->timestamp_begin);
+       ret = ustctl_get_timestamp_begin(ustream, &timestamp_begin);
        if (ret < 0) {
                PERROR("ustctl_get_timestamp_begin");
                goto error;
        }
-       index->timestamp_begin = htobe64(index->timestamp_begin);
 
-       ret = ustctl_get_timestamp_end(ustream, &index->timestamp_end);
+       ret = ustctl_get_timestamp_end(ustream, &timestamp_end);
        if (ret < 0) {
                PERROR("ustctl_get_timestamp_end");
                goto error;
        }
-       index->timestamp_end = htobe64(index->timestamp_end);
 
-       ret = ustctl_get_events_discarded(ustream, &index->events_discarded);
+       ret = ustctl_get_events_discarded(ustream, &events_discarded);
        if (ret < 0) {
                PERROR("ustctl_get_events_discarded");
                goto error;
        }
-       index->events_discarded = htobe64(index->events_discarded);
 
-       ret = ustctl_get_content_size(ustream, &index->content_size);
+       ret = ustctl_get_content_size(ustream, &content_size);
        if (ret < 0) {
                PERROR("ustctl_get_content_size");
                goto error;
        }
-       index->content_size = htobe64(index->content_size);
 
-       ret = ustctl_get_packet_size(ustream, &index->packet_size);
+       ret = ustctl_get_packet_size(ustream, &packet_size);
        if (ret < 0) {
                PERROR("ustctl_get_packet_size");
                goto error;
        }
-       index->packet_size = htobe64(index->packet_size);
 
-       ret = ustctl_get_stream_id(ustream, &index->stream_id);
+       ret = ustctl_get_stream_id(ustream, &stream_id);
        if (ret < 0) {
                PERROR("ustctl_get_stream_id");
                goto error;
        }
-       index->stream_id = htobe64(index->stream_id);
 
-       ret = ustctl_get_instance_id(ustream, &index->stream_instance_id);
+       ret = ustctl_get_instance_id(ustream, &stream_instance_id);
        if (ret < 0) {
                PERROR("ustctl_get_instance_id");
                goto error;
        }
-       index->stream_instance_id = htobe64(index->stream_instance_id);
 
-       ret = ustctl_get_sequence_number(ustream, &index->packet_seq_num);
+       ret = ustctl_get_sequence_number(ustream, &packet_seq_num);
        if (ret < 0) {
                PERROR("ustctl_get_sequence_number");
                goto error;
        }
-       index->packet_seq_num = htobe64(index->packet_seq_num);
+
+       *index = (typeof(*index)) {
+               .offset = index->offset,
+               .packet_size = htobe64(packet_size),
+               .content_size = htobe64(content_size),
+               .timestamp_begin = htobe64(timestamp_begin),
+               .timestamp_end = htobe64(timestamp_end),
+               .events_discarded = htobe64(events_discarded),
+               .stream_id = htobe64(stream_id),
+               .stream_instance_id = htobe64(stream_instance_id),
+               .packet_seq_num = htobe64(packet_seq_num),
+       };
 
 error:
        return ret;