tracing/osnoise: Fix resetting of tracepoints

JIRA: https://issues.redhat.com/browse/RHEL-86682
CVE: CVE-2025-21733

commit e3ff424
Author: Steven Rostedt <[email protected]>
Date:   Thu Jan 23 20:41:59 2025 -0500

    tracing/osnoise: Fix resetting of tracepoints

    If a timerlat tracer is started with the osnoise option OSNOISE_WORKLOAD
    disabled, but then that option is enabled and timerlat is removed, the
    tracepoints that were enabled on timerlat registration do not get
    disabled. If the option is disabled again and timelat is started, then it
    triggers a warning in the tracepoint code due to registering the
    tracepoint again without ever disabling it.

    Do not use the same user space defined options to know to disable the
    tracepoints when timerlat is removed. Instead, set a global flag when it
    is enabled and use that flag to know to disable the events.

     ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
     ~# echo timerlat > /sys/kernel/tracing/current_tracer
     ~# echo OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
     ~# echo nop > /sys/kernel/tracing/current_tracer
     ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
     ~# echo timerlat > /sys/kernel/tracing/current_tracer

    Triggers:

     ------------[ cut here ]------------
     WARNING: CPU: 6 PID: 1337 at kernel/tracepoint.c:294 tracepoint_add_func+0x3b6/0x3f0
     Modules linked in:
     CPU: 6 UID: 0 PID: 1337 Comm: rtla Not tainted 6.13.0-rc4-test-00018-ga867c441128e-dirty #73
     Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
     RIP: 0010:tracepoint_add_func+0x3b6/0x3f0
     Code: 48 8b 53 28 48 8b 73 20 4c 89 04 24 e8 23 59 11 00 4c 8b 04 24 e9 36 fe ff ff 0f 0b b8 ea ff ff ff 45 84 e4 0f 84 68 fe ff ff <0f> 0b e9 61 fe ff ff 48 8b 7b 18 48 85 ff 0f 84 4f ff ff ff 49 8b
     RSP: 0018:ffffb9b003a87ca0 EFLAGS: 00010202
     RAX: 00000000ffffffef RBX: ffffffff92f30860 RCX: 0000000000000000
     RDX: 0000000000000000 RSI: ffff9bf59e91ccd0 RDI: ffffffff913b6410
     RBP: 000000000000000a R08: 00000000000005c7 R09: 0000000000000002
     R10: ffffb9b003a87ce0 R11: 0000000000000002 R12: 0000000000000001
     R13: ffffb9b003a87ce0 R14: ffffffffffffffef R15: 0000000000000008
     FS:  00007fce81209240(0000) GS:ffff9bf6fdd00000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
     CR2: 000055e99b728000 CR3: 00000001277c0002 CR4: 0000000000172ef0
     Call Trace:
      <TASK>
      ? __warn.cold+0xb7/0x14d
      ? tracepoint_add_func+0x3b6/0x3f0
      ? report_bug+0xea/0x170
      ? handle_bug+0x58/0x90
      ? exc_invalid_op+0x17/0x70
      ? asm_exc_invalid_op+0x1a/0x20
      ? __pfx_trace_sched_migrate_callback+0x10/0x10
      ? tracepoint_add_func+0x3b6/0x3f0
      ? __pfx_trace_sched_migrate_callback+0x10/0x10
      ? __pfx_trace_sched_migrate_callback+0x10/0x10
      tracepoint_probe_register+0x78/0xb0
      ? __pfx_trace_sched_migrate_callback+0x10/0x10
      osnoise_workload_start+0x2b5/0x370
      timerlat_tracer_init+0x76/0x1b0
      tracing_set_tracer+0x244/0x400
      tracing_set_trace_write+0xa0/0xe0
      vfs_write+0xfc/0x570
      ? do_sys_openat2+0x9c/0xe0
      ksys_write+0x72/0xf0
      do_syscall_64+0x79/0x1c0
      entry_SYSCALL_64_after_hwframe+0x76/0x7e

    Cc: [email protected]
    Cc: Masami Hiramatsu <[email protected]>
    Cc: Mathieu Desnoyers <[email protected]>
    Cc: Tomas Glozar <[email protected]>
    Cc: Gabriele Monaco <[email protected]>
    Cc: Luis Goncalves <[email protected]>
    Cc: John Kacur <[email protected]>
    Link: https://lore.kernel.org/[email protected]
    Fixes: e88ed22 ("tracing/timerlat: Add user-space interface")
    Signed-off-by: Steven Rostedt (Google) <[email protected]>

Signed-off-by: Jerome Marchand <[email protected]>

Author: jeromemarchand

kernel/trace/trace_osnoise.c

@@ -1235,6 +1235,8 @@ static void trace_sched_migrate_callback(void *data, struct task_struct *p, int
 	}
 }
 
+static bool monitor_enabled;
+
 static int register_migration_monitor(void)
 {
 	int ret = 0;
@@ -1243,16 +1245,25 @@ static int register_migration_monitor(void)
 	 * Timerlat thread migration check is only required when running timerlat in user-space.
 	 * Thus, enable callback only if timerlat is set with no workload.
 	 */
-	if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options))
+	if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options)) {
+		if (WARN_ON_ONCE(monitor_enabled))
+			return 0;
+
 		ret = register_trace_sched_migrate_task(trace_sched_migrate_callback, NULL);
+		if (!ret)
+			monitor_enabled = true;
+	}
 
 	return ret;
 }
 
 static void unregister_migration_monitor(void)
 {
-	if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options))
-		unregister_trace_sched_migrate_task(trace_sched_migrate_callback, NULL);
+	if (!monitor_enabled)
+		return;
+
+	unregister_trace_sched_migrate_task(trace_sched_migrate_callback, NULL);
+	monitor_enabled = false;
 }
 #else
 static int register_migration_monitor(void)