diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8658cad53cb5..e4a490d3d08c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7717,12 +7717,55 @@ trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt, return cnt; } +static bool tr_option_match(struct trace_array *tr, void *topt) +{ + for (int i = 0; i < tr->nr_topts; i++) { + struct trace_options *tr_topts = &tr->topts[i]; + + if (topt >= (void *)&tr_topts->topts[0] && + topt < (void *)&tr_topts->topts[tr_topts->nr_topts]) + return true; + } + return false; +} + +/* + * The topt is the address of a trace_array->topts[] element that holds the + * the tracer options descriptor. But since the trace_array reference has not + * been taken yet, it cannot be dereferenced as it could have been freed by + * a rmdir of the instance the trace_array represents. + * + * Search the list of trace_arrays and compare the topt to the address of + * the entire trace_array topts array for each trace_array in the list. + * If one is matched, then take the reference and return it. If not, the + * trace_array no longer exits. + */ +static int trace_array_tracer_options_get(void *topt) +{ + struct trace_array *tr; + int ret; + + ret = security_locked_down(LOCKDOWN_TRACEFS); + if (ret) + return ret; + + if (tracing_disabled) + return -ENODEV; + + guard(mutex)(&trace_types_lock); + list_for_each_entry(tr, &ftrace_trace_arrays, list) { + if (tr_option_match(tr, topt)) + return __trace_array_get(tr); + } + return -ENODEV; +} + static int tracing_open_options(struct inode *inode, struct file *filp) { struct trace_option_dentry *topt = inode->i_private; int ret; - ret = tracing_check_open_get_tr(topt->tr); + ret = trace_array_tracer_options_get(topt); if (ret) return ret; @@ -7984,6 +8027,7 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer, tr->topts = tr_topts; tr->topts[tr->nr_topts].tracer = tracer; tr->topts[tr->nr_topts].topts = topts; + tr->topts[tr->nr_topts].nr_topts = cnt; tr->nr_topts++; for (cnt = 0; opts[cnt].name; cnt++) { diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 5e76f94e7a80..bd3c8f80300f 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -227,6 +227,7 @@ struct array_buffer { struct trace_options { struct tracer *tracer; struct trace_option_dentry *topts; + int nr_topts; }; struct trace_pid_list *trace_pid_list_alloc(void);