tracing: Have tracing_max_latency inc the trace array ref count

commit 7d660c9b2bc95107f90a9f4c4759be85309a6550 upstream.

The tracing_max_latency file points to the trace_array max_latency field.
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 tracing_max_latency is opened.

Link: https://lkml.kernel.org/r/20230907024803.666889383@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 54ccdca395311803aa2e777346d3282762cc5b70..a9a54581694efd1b2b36bcc41084a496278019a4 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1729,7 +1729,7 @@ static void trace_create_maxlat_file(struct trace_array *tr,
        init_irq_work(&tr->fsnotify_irqwork, latency_fsnotify_workfn_irq);
        tr->d_max_latency = trace_create_file("tracing_max_latency",
                                              TRACE_MODE_WRITE,
-                                             d_tracer, &tr->max_latency,
+                                             d_tracer, tr,
                                              &tracing_max_lat_fops);
 }
 
@@ -1762,7 +1762,7 @@ void latency_fsnotify(struct trace_array *tr)
 
 #define trace_create_maxlat_file(tr, d_tracer)                         \
        trace_create_file("tracing_max_latency", TRACE_MODE_WRITE,      \
-                         d_tracer, &tr->max_latency, &tracing_max_lat_fops)
+                         d_tracer, tr, &tracing_max_lat_fops)
 
 #endif
 
@@ -6604,14 +6604,18 @@ static ssize_t
 tracing_max_lat_read(struct file *filp, char __user *ubuf,
                     size_t cnt, loff_t *ppos)
 {
-       return tracing_nsecs_read(filp->private_data, ubuf, cnt, ppos);
+       struct trace_array *tr = filp->private_data;
+
+       return tracing_nsecs_read(&tr->max_latency, ubuf, cnt, ppos);
 }
 
 static ssize_t
 tracing_max_lat_write(struct file *filp, const char __user *ubuf,
                      size_t cnt, loff_t *ppos)
 {
-       return tracing_nsecs_write(filp->private_data, ubuf, cnt, ppos);
+       struct trace_array *tr = filp->private_data;
+
+       return tracing_nsecs_write(&tr->max_latency, ubuf, cnt, ppos);
 }
 
 #endif
@@ -7668,10 +7672,11 @@ static const struct file_operations tracing_thresh_fops = {
 
 #ifdef CONFIG_TRACER_MAX_TRACE
 static const struct file_operations tracing_max_lat_fops = {
-       .open           = tracing_open_generic,
+       .open           = tracing_open_generic_tr,
        .read           = tracing_max_lat_read,
        .write          = tracing_max_lat_write,
        .llseek         = generic_file_llseek,
+       .release        = tracing_release_generic_tr,
 };
 #endif