[PATCH AUTOSEL 5.4 043/330] tracing: Verify if trace array exists before destroying it.

Sasha Levin
2020-09-18T03:13:20Z

From: Divya Indi <divya.indi@oracle.com>

[ Upstream commit e585e6469d6f476b82aa148dc44aaf7ae269a4e2 ]

A trace array can be destroyed from userspace or kernel. Verify if the
trace array exists before proceeding to destroy/remove it.

Link: http://lkml.kernel.org/r/1565805327-579-3-git-send-email-divya.indi@oracle.com

Reviewed-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Divya Indi <divya.indi@oracle.com>
[ Removed unneeded braces ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/module.c | 6 +++++-
kernel/trace/trace.c | 15 ++++++++++++---
2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 819c5d3b4c295..0e3743dd3a568 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3753,7 +3753,6 @@ static int complete_formation(struct module *mod, struct load_info *info)

module_enable_ro(mod, false);
module_enable_nx(mod);
- module_enable_x(mod);

/* Mark state as coming so strong_try_module_get() ignores us,
* but kallsyms etc. can see us. */
@@ -3776,6 +3775,11 @@ static int prepare_coming_module(struct module *mod)
if (err)
return err;

+ /* Make module executable after ftrace is enabled */
+ mutex_lock(&module_mutex);
+ module_enable_x(mod);
+ mutex_unlock(&module_mutex);
+
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
return 0;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f9c2bdbbd8936..cd3d91554aff1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8502,17 +8502,26 @@ static int __remove_instance(struct trace_array *tr)
return 0;
}

-int trace_array_destroy(struct trace_array *tr)
+int trace_array_destroy(struct trace_array *this_tr)
{
+ struct trace_array *tr;
int ret;

- if (!tr)
+ if (!this_tr)
return -EINVAL;

mutex_lock(&event_mutex);
mutex_lock(&trace_types_lock);

- ret = __remove_instance(tr);
+ ret = -ENODEV;
+
+ /* Making sure trace array exists before destroying it. */
+ list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+ if (tr == this_tr) {
+ ret = __remove_instance(tr);
+ break;
+ }
+ }

mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);
--
2.25.1