From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Mon, 1 Mar 2021 18:07:27 +0000 (-0500)
Subject: Fix: lttng_event_notifier_group_error_counter_cmd does not respect caller convention
X-Git-Tag: v2.13.0-rc1~364
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=ba5b3d2bf3ecd8614e74efc1db2f5a626c5d9a92;p=lttng-ust.git

Fix: lttng_event_notifier_group_error_counter_cmd does not respect caller convention

The callers of lttng_event_notifier_group_error_counter_cmd (via
callback) expects that, on success, the object for which the ownership was
taken be set to -1 or NULL.

In this case, the shm_fd filed was not set to -1. Resulting in the
caller closing the fd and leading to errors on subsequent call.

e.g:
 sample: lttng-ust-fd-tracker.c:300: int lttng_ust_add_fd_to_tracker(int): Assertion `!IS_FD_SET(fd, lttng_fd_set)' failed.
 Error: Error sending counter cpu data to UST tracer: status=APP_DEAD
 Error: Failed to setup event notifier error accounting for app
 ./test.sh: line 5: 2650455 Aborted                 (core dumped) ../lttng-ust/doc/examples/easy-ust/sample
 lttng-sessiond: ustctl.c:192: int ustctl_release_object(int, struct lttng_ust_object_data *): Assertion `0' failed.

Change-Id: I79b242768cf7d27cd9a50c31b56423c8de08abd5
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/liblttng-ust/lttng-ust-abi.c b/liblttng-ust/lttng-ust-abi.c
index 62e1be74..8fd2e958 100644
--- a/liblttng-ust/lttng-ust-abi.c
+++ b/liblttng-ust/lttng-ust-abi.c
@@ -733,21 +733,32 @@ static
 long lttng_event_notifier_group_error_counter_cmd(int objd, unsigned int cmd, unsigned long arg,
 	union ust_args *uargs, void *owner)
 {
+	int ret;
 	struct lttng_counter *counter = objd_private(objd);
 
 	switch (cmd) {
 	case LTTNG_UST_COUNTER_GLOBAL:
-		return -EINVAL;		/* Unimplemented. */
+		ret = -EINVAL;	/* Unimplemented. */
+		break;
 	case LTTNG_UST_COUNTER_CPU:
 	{
 		struct lttng_ust_counter_cpu *counter_cpu =
 			(struct lttng_ust_counter_cpu *)arg;
-		return lttng_counter_set_cpu_shm(counter->counter,
+
+		ret = lttng_counter_set_cpu_shm(counter->counter,
 			counter_cpu->cpu_nr, uargs->counter_shm.shm_fd);
+		if (!ret) {
+			/* Take ownership of the shm_fd. */
+			uargs->counter_shm.shm_fd = -1;
+		}
+		break;
 	}
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
+		break;
 	}
+
+	return ret;
 }
 
 LTTNG_HIDDEN