From 8aafa51cb714fb16989089d4bc1ea7e7eb50124c Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Wed, 13 Dec 2023 09:35:27 -0500
Subject: [PATCH] rts/eventlog: Place upper bound on IPE string field lengths
The strings in IPE events may be of unbounded length. Limit the lengths
of these fields to 64k characters to ensure that we don't exceed the
maximum event length.
---
rts/eventlog/EventLog.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/rts/eventlog/EventLog.c b/rts/eventlog/EventLog.c
index bb2ad4106366..1f7472b0fd73 100644
--- a/rts/eventlog/EventLog.c
+++ b/rts/eventlog/EventLog.c
@@ -27,6 +27,8 @@
#include <unistd.h>
#endif
+#define MIN(x,y) ((x) < (y) ? (x) : (y))
+
Mutex state_change_mutex;
bool eventlog_enabled; // protected by state_change_mutex to ensure
// serialisation of calls to
@@ -85,6 +87,14 @@ bool eventlog_enabled; // protected by state_change_mutex to ensure
* case is that we must ensure that the buffers of any disabled capabilities are
* flushed, lest their events are stuck in limbo. This is achieved with a call to
* flushLocalEventsBuf in traceCapDisable.
+ *
+ *
+ * Note [Maximum event length]
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * The maximum length of an eventlog event is determined by the maximum event
+ * buffer size, EVENT_LOG_SIZE. We must ensure that no variable-length event
+ * exceeds this limit. For this reason we impose maximum length limits on
+ * fields which may have unbounded values.
*/
static const EventLogWriter *event_log_writer = NULL;
@@ -93,6 +103,7 @@ static const EventLogWriter *event_log_writer = NULL;
// eventlog is restarted
static eventlog_init_func_t *eventlog_header_funcs = NULL;
+// See Note [Maximum event length]
#define EVENT_LOG_SIZE 2 * (1024 * 1024) // 2MB
static int flushCount = 0;
@@ -1440,14 +1451,16 @@ void postTickyCounterSamples(StgEntCounter *counters)
#endif /* TICKY_TICKY */
void postIPE(const InfoProvEnt *ipe)
{
+ // See Note [Maximum event length].
+ const StgWord MAX_IPE_STRING_LEN = 65535;
ACQUIRE_LOCK(&eventBufMutex);
- StgWord table_name_len = strlen(ipe->prov.table_name);
- StgWord closure_desc_len = strlen(ipe->prov.closure_desc);
- StgWord ty_desc_len = strlen(ipe->prov.ty_desc);
- StgWord label_len = strlen(ipe->prov.label);
- StgWord module_len = strlen(ipe->prov.module);
- StgWord src_file_len = strlen(ipe->prov.src_file);
- StgWord src_span_len = strlen(ipe->prov.src_span);
+ StgWord table_name_len = MIN(strlen(ipe->prov.table_name), MAX_IPE_STRING_LEN);
+ StgWord closure_desc_len = MIN(strlen(ipe->prov.closure_desc), MAX_IPE_STRING_LEN);
+ StgWord ty_desc_len = MIN(strlen(ipe->prov.ty_desc), MAX_IPE_STRING_LEN);
+ StgWord label_len = MIN(strlen(ipe->prov.label), MAX_IPE_STRING_LEN);
+ StgWord module_len = MIN(strlen(ipe->prov.module), MAX_IPE_STRING_LEN);
+ StgWord src_file_len = MIN(strlen(ipe->prov.src_file), MAX_IPE_STRING_LEN);
+ StgWord src_span_len = MIN(strlen(ipe->prov.src_span), MAX_IPE_STRING_LEN);
// 8 for the info word
// 1 null after each string
--
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