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tracing: probes: Fix a possible race in trace_probe_log APIs
[ Upstream commitfd837de3c9
] Since the shared trace_probe_log variable can be accessed and modified via probe event create operation of kprobe_events, uprobe_events, and dynamic_events, it should be protected. In the dynamic_events, all operations are serialized by `dyn_event_ops_mutex`. But kprobe_events and uprobe_events interfaces are not serialized. To solve this issue, introduces dyn_event_create(), which runs create() operation under the mutex, for kprobe_events and uprobe_events. This also uses lockdep to check the mutex is held when using trace_probe_log* APIs. Link: https://lore.kernel.org/all/174684868120.551552.3068655787654268804.stgit@devnote2/ Reported-by: Paul Cacheux <paulcacheux@gmail.com> Closes: https://lore.kernel.org/all/20250510074456.805a16872b591e2971a4d221@kernel.org/ Fixes:ab105a4fb8
("tracing: Use tracing error_log with probe events") Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -16,7 +16,7 @@
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#include "trace_output.h" /* for trace_event_sem */
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#include "trace_dynevent.h"
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static DEFINE_MUTEX(dyn_event_ops_mutex);
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DEFINE_MUTEX(dyn_event_ops_mutex);
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static LIST_HEAD(dyn_event_ops_list);
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bool trace_event_dyn_try_get_ref(struct trace_event_call *dyn_call)
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@ -125,6 +125,20 @@ out:
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return ret;
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}
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/*
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* Locked version of event creation. The event creation must be protected by
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* dyn_event_ops_mutex because of protecting trace_probe_log.
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*/
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int dyn_event_create(const char *raw_command, struct dyn_event_operations *type)
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{
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int ret;
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mutex_lock(&dyn_event_ops_mutex);
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ret = type->create(raw_command);
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mutex_unlock(&dyn_event_ops_mutex);
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return ret;
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}
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static int create_dyn_event(const char *raw_command)
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{
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struct dyn_event_operations *ops;
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@ -100,6 +100,7 @@ void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
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void dyn_event_seq_stop(struct seq_file *m, void *v);
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int dyn_events_release_all(struct dyn_event_operations *type);
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int dyn_event_release(const char *raw_command, struct dyn_event_operations *type);
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int dyn_event_create(const char *raw_command, struct dyn_event_operations *type);
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/*
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* for_each_dyn_event - iterate over the dyn_event list
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@ -1090,7 +1090,7 @@ static int create_or_delete_trace_kprobe(const char *raw_command)
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if (raw_command[0] == '-')
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return dyn_event_release(raw_command, &trace_kprobe_ops);
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ret = trace_kprobe_create(raw_command);
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ret = dyn_event_create(raw_command, &trace_kprobe_ops);
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return ret == -ECANCELED ? -EINVAL : ret;
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}
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@ -154,9 +154,12 @@ fail:
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}
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static struct trace_probe_log trace_probe_log;
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extern struct mutex dyn_event_ops_mutex;
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void trace_probe_log_init(const char *subsystem, int argc, const char **argv)
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{
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lockdep_assert_held(&dyn_event_ops_mutex);
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trace_probe_log.subsystem = subsystem;
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trace_probe_log.argc = argc;
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trace_probe_log.argv = argv;
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@ -165,11 +168,15 @@ void trace_probe_log_init(const char *subsystem, int argc, const char **argv)
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void trace_probe_log_clear(void)
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{
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lockdep_assert_held(&dyn_event_ops_mutex);
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memset(&trace_probe_log, 0, sizeof(trace_probe_log));
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}
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void trace_probe_log_set_index(int index)
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{
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lockdep_assert_held(&dyn_event_ops_mutex);
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trace_probe_log.index = index;
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}
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@ -178,6 +185,8 @@ void __trace_probe_log_err(int offset, int err_type)
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char *command, *p;
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int i, len = 0, pos = 0;
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lockdep_assert_held(&dyn_event_ops_mutex);
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if (!trace_probe_log.argv)
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return;
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@ -739,7 +739,7 @@ static int create_or_delete_trace_uprobe(const char *raw_command)
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if (raw_command[0] == '-')
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return dyn_event_release(raw_command, &trace_uprobe_ops);
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ret = trace_uprobe_create(raw_command);
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ret = dyn_event_create(raw_command, &trace_uprobe_ops);
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return ret == -ECANCELED ? -EINVAL : ret;
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}
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