On Sat, 10 May 2025 12:44:41 +0900 "Masami Hiramatsu (Google)" <[email protected]> wrote:
> From: Masami Hiramatsu (Google) <[email protected]> > > 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. > > Reported-by: Paul Cacheux <[email protected]> > Closes: > https://lore.kernel.org/all/[email protected]/ BTW, this fixes the problem introduced by commit ab105a4fb894 ("tracing: Use tracing error_log with probe events"). However, this patch can be applied after commit d262271d0483 ("tracing/dynevent: Delegate parsing to create function"). Thus, before that commit, we may need another way to fix this issue. (e.g. introduce a different mutex.) Anyway, to record the correct fixes; Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe events") Thanks, > Signed-off-by: Masami Hiramatsu (Google) <[email protected]> > --- > kernel/trace/trace_dynevent.c | 16 +++++++++++++++- > kernel/trace/trace_dynevent.h | 1 + > kernel/trace/trace_kprobe.c | 2 +- > kernel/trace/trace_probe.c | 9 +++++++++ > kernel/trace/trace_uprobe.c | 2 +- > 5 files changed, 27 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c > index a322e4f249a5..5d64a18cacac 100644 > --- a/kernel/trace/trace_dynevent.c > +++ b/kernel/trace/trace_dynevent.c > @@ -16,7 +16,7 @@ > #include "trace_output.h" /* for trace_event_sem */ > #include "trace_dynevent.h" > > -static DEFINE_MUTEX(dyn_event_ops_mutex); > +DEFINE_MUTEX(dyn_event_ops_mutex); > static LIST_HEAD(dyn_event_ops_list); > > bool trace_event_dyn_try_get_ref(struct trace_event_call *dyn_call) > @@ -116,6 +116,20 @@ int dyn_event_release(const char *raw_command, struct > dyn_event_operations *type > return ret; > } > > +/* > + * Locked version of event creation. The event creation must be protected by > + * dyn_event_ops_mutex because of protecting trace_probe_log. > + */ > +int dyn_event_create(const char *raw_command, struct dyn_event_operations > *type) > +{ > + int ret; > + > + mutex_lock(&dyn_event_ops_mutex); > + ret = type->create(raw_command); > + mutex_unlock(&dyn_event_ops_mutex); > + return ret; > +} > + > static int create_dyn_event(const char *raw_command) > { > struct dyn_event_operations *ops; > diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h > index 936477a111d3..beee3f8d7544 100644 > --- a/kernel/trace/trace_dynevent.h > +++ b/kernel/trace/trace_dynevent.h > @@ -100,6 +100,7 @@ void *dyn_event_seq_next(struct seq_file *m, void *v, > loff_t *pos); > void dyn_event_seq_stop(struct seq_file *m, void *v); > int dyn_events_release_all(struct dyn_event_operations *type); > int dyn_event_release(const char *raw_command, struct dyn_event_operations > *type); > +int dyn_event_create(const char *raw_command, struct dyn_event_operations > *type); > > /* > * for_each_dyn_event - iterate over the dyn_event list > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 2703b96d8990..3e5c47b6d7b2 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -1089,7 +1089,7 @@ static int create_or_delete_trace_kprobe(const char > *raw_command) > if (raw_command[0] == '-') > return dyn_event_release(raw_command, &trace_kprobe_ops); > > - ret = trace_kprobe_create(raw_command); > + ret = dyn_event_create(raw_command, &trace_kprobe_ops); > return ret == -ECANCELED ? -EINVAL : ret; > } > > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c > index 2eeecb6c95ee..424751cdf31f 100644 > --- a/kernel/trace/trace_probe.c > +++ b/kernel/trace/trace_probe.c > @@ -154,9 +154,12 @@ static const struct fetch_type *find_fetch_type(const > char *type, unsigned long > } > > static struct trace_probe_log trace_probe_log; > +extern struct mutex dyn_event_ops_mutex; > > void trace_probe_log_init(const char *subsystem, int argc, const char **argv) > { > + lockdep_assert_held(&dyn_event_ops_mutex); > + > trace_probe_log.subsystem = subsystem; > trace_probe_log.argc = argc; > trace_probe_log.argv = argv; > @@ -165,11 +168,15 @@ void trace_probe_log_init(const char *subsystem, int > argc, const char **argv) > > void trace_probe_log_clear(void) > { > + lockdep_assert_held(&dyn_event_ops_mutex); > + > memset(&trace_probe_log, 0, sizeof(trace_probe_log)); > } > > void trace_probe_log_set_index(int index) > { > + lockdep_assert_held(&dyn_event_ops_mutex); > + > trace_probe_log.index = index; > } > > @@ -178,6 +185,8 @@ void __trace_probe_log_err(int offset, int err_type) > char *command, *p; > int i, len = 0, pos = 0; > > + lockdep_assert_held(&dyn_event_ops_mutex); > + > if (!trace_probe_log.argv) > return; > > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c > index 3386439ec9f6..35cf76c75dd7 100644 > --- a/kernel/trace/trace_uprobe.c > +++ b/kernel/trace/trace_uprobe.c > @@ -741,7 +741,7 @@ static int create_or_delete_trace_uprobe(const char > *raw_command) > if (raw_command[0] == '-') > return dyn_event_release(raw_command, &trace_uprobe_ops); > > - ret = trace_uprobe_create(raw_command); > + ret = dyn_event_create(raw_command, &trace_uprobe_ops); > return ret == -ECANCELED ? -EINVAL : ret; > } > > -- Masami Hiramatsu (Google) <[email protected]>
