[PATCH AUTOSEL 6.6 16/20] greybus: Fix use-after-free bug in gb_interface_release due to race condition.

Sasha Levin
2024-06-05T11:53:07Z

From: Sicong Huang <congei42@163.com>

[ Upstream commit 5c9c5d7f26acc2c669c1dcf57d1bb43ee99220ce ]

In gb_interface_create, &intf->mode_switch_completion is bound with
gb_interface_mode_switch_work. Then it will be started by
gb_interface_request_mode_switch. Here is the relevant code.
if (!queue_work(system_long_wq, &intf->mode_switch_work)) {
...
}

If we call gb_interface_release to make cleanup, there may be an
unfinished work. This function will call kfree to free the object
"intf". However, if gb_interface_mode_switch_work is scheduled to
run after kfree, it may cause use-after-free error as
gb_interface_mode_switch_work will use the object "intf".
The possible execution flow that may lead to the issue is as follows:

CPU0 CPU1

| gb_interface_create
| gb_interface_request_mode_switch
gb_interface_release |
kfree(intf) (free) |
| gb_interface_mode_switch_work
| mutex_lock(&intf->mutex) (use)

Fix it by canceling the work before kfree.

Signed-off-by: Sicong Huang <congei42@163.com>
Link: https://lore.kernel.org/r/20240416080313.92306-1-congei42@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/greybus/interface.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/greybus/interface.c b/drivers/greybus/interface.c
index 9ec949a438ef6..52ef6be9d4499 100644
--- a/drivers/greybus/interface.c
+++ b/drivers/greybus/interface.c
@@ -694,6 +694,7 @@ static void gb_interface_release(struct device *dev)

trace_gb_interface_release(intf);

+ cancel_work_sync(&intf->mode_switch_work);
kfree(intf);
}

--
2.43.0