From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Thu, 12 Sep 2019 14:23:23 +0000 (-0400)
Subject: lttng-sessiond: clean-up: set free'd pointer to NULL
X-Git-Tag: v2.11.0-rc4~45
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=3577d7d8ecbe2ded93572fcf38ea555bd3d04722;p=lttng-tools.git

lttng-sessiond: clean-up: set free'd pointer to NULL

Set the wait_node and ust_cmd pointers to NULL after they have been
free'd to make this function easier to follow. This may also help
scan-build analyze this function as it gets confused about the values
of those variables. Currently, scan-build (clang 8.0.1) reports a
use-after free of both variables when 'app' is simultaneously null and
non-null... you read that right.

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

diff --git a/src/bin/lttng-sessiond/dispatch.c b/src/bin/lttng-sessiond/dispatch.c
index a637f23de..bfe4455b5 100644
--- a/src/bin/lttng-sessiond/dispatch.c
+++ b/src/bin/lttng-sessiond/dispatch.c
@@ -304,6 +304,7 @@ static void *thread_dispatch_ust_registration(void *data)
 					}
 					lttng_fd_put(LTTNG_FD_APPS, 1);
 					free(ust_cmd);
+					ust_cmd = NULL;
 					goto error;
 				}
 				CDS_INIT_LIST_HEAD(&wait_node->head);
@@ -318,7 +319,9 @@ static void *thread_dispatch_ust_registration(void *data)
 					}
 					lttng_fd_put(LTTNG_FD_APPS, 1);
 					free(wait_node);
+					wait_node = NULL;
 					free(ust_cmd);
+					ust_cmd = NULL;
 					continue;
 				}
 				/*
@@ -329,6 +332,7 @@ static void *thread_dispatch_ust_registration(void *data)
 				wait_queue.count++;
 
 				free(ust_cmd);
+				ust_cmd = NULL;
 				/*
 				 * We have to continue here since we don't have the notify
 				 * socket and the application MUST be added to the hash table
@@ -349,6 +353,7 @@ static void *thread_dispatch_ust_registration(void *data)
 						wait_queue.count--;
 						app = wait_node->app;
 						free(wait_node);
+						wait_node = NULL;
 						DBG3("UST app notify socket %d is set", ust_cmd->sock);
 						break;
 					}
@@ -367,6 +372,7 @@ static void *thread_dispatch_ust_registration(void *data)
 					lttng_fd_put(LTTNG_FD_APPS, 1);
 				}
 				free(ust_cmd);
+				ust_cmd = NULL;
 			}
 
 			if (app) {