From: Francis Deslauriers <francis.deslauriers@efficios.com>
Date: Fri, 28 May 2021 20:06:09 +0000 (-0400)
Subject: Fix: appending unallocated data from beyond exclusion entries
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=1085f5eafd7f240089e410d94cb3f8b9fa19a090

Fix: appending unallocated data from beyond exclusion entries

Issue
=====
If an exclusion string is smaller than the `LTTNG_SYMBOL_NAME_LEN`
integer, the `lttng_dynamic_buffer_append()` call will append
unallocated data to the buffer.

Fix
===
Use the `exclusion_len` value to copy the actual exclusion and pad the
remaining bytes with zeros.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I04c6681c28e82de29791541eb490158db9e503d0
---

diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index d9805e222..7ad1fe132 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -1204,7 +1204,7 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 	for (i = 0; i < exclusion_count; i++) {
 		size_t exclusion_len;
 
-		exclusion_len = lttng_strnlen(*(exclusion_list + i),
+		exclusion_len = lttng_strnlen(exclusion_list[i],
 				LTTNG_SYMBOL_NAME_LEN);
 		if (exclusion_len == LTTNG_SYMBOL_NAME_LEN) {
 			/* Exclusion is not NULL-terminated. */
@@ -1213,7 +1213,17 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 		}
 
 		ret = lttng_dynamic_buffer_append(&payload.buffer,
-				*(exclusion_list + i), LTTNG_SYMBOL_NAME_LEN);
+				exclusion_list[i], exclusion_len);
+		if (ret) {
+			goto mem_error;
+		}
+
+		/*
+		 * Padding the rest of the entry with zeros. Every exclusion
+		 * entries take LTTNG_SYMBOL_NAME_LEN bytes in the buffer.
+		 */
+		ret = lttng_dynamic_buffer_set_size(&payload.buffer,
+				LTTNG_SYMBOL_NAME_LEN * (i + 1));
 		if (ret) {
 			goto mem_error;
 		}