From: Mathieu Desnoyers Date: Tue, 19 Feb 2019 22:47:49 +0000 (-0500) Subject: Fix: consumer snapshot: handle unsigned long overflow X-Git-Tag: v2.11.0-rc2~50 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=0fdaf1ed3f288f99614a3f0b04b2da1a2ce6eedb;p=lttng-tools.git Fix: consumer snapshot: handle unsigned long overflow Comparing the consumed iterator and the produced position without using a difference generates an empty snapshot when the iterator is before unsigned long overflow and the produced position is after unsigned long overflow. This applies to both UST and kernel consumers. Signed-off-by: Mathieu Desnoyers Signed-off-by: Jérémie Galarneau --- diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c index 4e93bee91..627cd2a8b 100644 --- a/src/common/kernel-consumer/kernel-consumer.c +++ b/src/common/kernel-consumer/kernel-consumer.c @@ -237,7 +237,7 @@ static int lttng_kconsumer_snapshot_channel( produced_pos, nb_packets_per_stream, stream->max_sb_size); - while (consumed_pos < produced_pos) { + while ((long) (consumed_pos - produced_pos) < 0) { ssize_t read_len; unsigned long len, padded_len; diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c index 46f330052..94b761cb8 100644 --- a/src/common/ust-consumer/ust-consumer.c +++ b/src/common/ust-consumer/ust-consumer.c @@ -1168,7 +1168,7 @@ static int snapshot_channel(struct lttng_consumer_channel *channel, produced_pos, nb_packets_per_stream, stream->max_sb_size); - while (consumed_pos < produced_pos) { + while ((long) (consumed_pos - produced_pos) < 0) { ssize_t read_len; unsigned long len, padded_len;