linux-kernel - [PATCH RFC v3 3/4] module: update state and release reference under lock

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Message-Id: <20241108-modules-ro_after_init-v3-3-6dd041b588a5@samsung.com>
Date: Fri, 08 Nov 2024 17:12:15 +0100
From: Daniel Gomez via B4 Relay <devnull+da.gomez.samsung.com@...nel.org>
To: Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>, 
 Sami Tolvanen <samitolvanen@...gle.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 Thomas Gleixner <tglx@...utronix.de>, Jinjie Ruan <ruanjinjie@...wei.com>, 
 Jens Axboe <axboe@...nel.dk>
Cc: "Daniel Gomez (Samsung)" <d+samsung@...ces.com>, 
 linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Daniel Gomez <da.gomez@...sung.com>
Subject: [PATCH RFC v3 3/4] module: update state and release reference
 under lock

From: Daniel Gomez <da.gomez@...sung.com>

Ensure the module state change and reference drop operations are
performed within module_mutex to prevent potential race conditions in
the failure path.

Signed-off-by: Daniel Gomez <da.gomez@...sung.com>
---
 kernel/module/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 35a50ded64a6..2b45a6efa0a9 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2994,10 +2994,12 @@ static noinline int do_init_module(struct module *mod)
 fail_free_freeinit:
 	kfree(freeinit);
 fail:
+	mutex_lock(&module_mutex);
 	/* Try to protect us from buggy refcounters. */
 	mod->state = MODULE_STATE_GOING;
-	synchronize_rcu();
 	module_put(mod);
+	mutex_unlock(&module_mutex);
+	synchronize_rcu();
 	blocking_notifier_call_chain(&module_notify_list,
 				     MODULE_STATE_GOING, mod);
 	klp_module_going(mod);

-- 
2.39.2