tracing: Have current_trace inc the trace array ref count

The current_trace updates the trace array tracer. For an instance, if the
file is opened and the instance is deleted, reading or writing to the file
will cause a use after free.

Up the ref count of the trace array when current_trace is opened.

Link: https://lkml.kernel.org/r/20230907024803.877687227@goodmis.org
Link: https://lore.kernel.org/all/1cb3aee2-19af-c472-e265-05176fe9bd84@huawei.com/
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Fixes: 8530dec63e7b4 ("tracing: Add tracing_check_open_get_tr()")
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c8b8b4c..b82df33 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7791,10 +7791,11 @@ static const struct file_operations tracing_max_lat_fops = {
 #endif
 
 static const struct file_operations set_tracer_fops = {
 #endif
 
 static const struct file_operations set_tracer_fops = {

-       .open           = tracing_open_generic,
+       .open           = tracing_open_generic_tr,

        .read           = tracing_set_trace_read,
        .write          = tracing_set_trace_write,
        .llseek         = generic_file_llseek,
        .read           = tracing_set_trace_read,
        .write          = tracing_set_trace_write,
        .llseek         = generic_file_llseek,

+       .release        = tracing_release_generic_tr,

 };
 
 static const struct file_operations tracing_pipe_fops = {
 };
 
 static const struct file_operations tracing_pipe_fops = {