linux-kernel - [PATCH] tracing: Track event ref in tracefs enable/disable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20221012215717.10492-1-beaub@linux.microsoft.com>
Date:   Wed, 12 Oct 2022 14:57:17 -0700
From:   Beau Belgrave <beaub@...ux.microsoft.com>
To:     rostedt@...dmis.org, mhiramat@...nel.org
Cc:     linux-trace-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] tracing: Track event ref in tracefs enable/disable

When events are enabled via the "enable" file within tracefs there is no
get or put ref. Add these to ensure modules and dynamic events do not
unload while the event is enabled via tracefs.

Signed-off-by: Beau Belgrave <beaub@...ux.microsoft.com>
---
 kernel/trace/trace_events.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 0356cae0cf74..f0b17adba1bc 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -634,6 +634,8 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 			}
 
 			call->class->reg(call, TRACE_REG_UNREGISTER, file);
+
+			trace_event_put_ref(call);
 		}
 		/* If in SOFT_MODE, just set the SOFT_DISABLE_BIT, else clear it */
 		if (file->flags & EVENT_FILE_FL_SOFT_MODE)
@@ -659,7 +661,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		}
 
 		if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
-			bool cmd = false, tgid = false;
+			bool cmd = false, tgid = false, put = false;
 
 			/* Keep the event disabled, when going to SOFT_MODE. */
 			if (soft_disable)
@@ -677,14 +679,22 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 				set_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
 			}
 
+			if (!trace_event_try_get_ref(call))
+				goto error_enabling;
+
+			put = true;
+
 			ret = call->class->reg(call, TRACE_REG_REGISTER, file);
 			if (ret) {
+error_enabling:
+				pr_info("event trace: Could not enable event "
+					"%s\n", trace_event_name(call));
 				if (cmd)
 					tracing_stop_cmdline_record();
 				if (tgid)
 					tracing_stop_tgid_record();
-				pr_info("event trace: Could not enable event "
-					"%s\n", trace_event_name(call));
+				if (put)
+					trace_event_put_ref(call);
 				break;
 			}
 			set_bit(EVENT_FILE_FL_ENABLED_BIT, &file->flags);

base-commit: 6c0f39e87b6ab1a3009e3a49d3e6f6db8dc756a8
-- 
2.25.1