linux-kernel - [PATCH v2 15/28] module: Use RCU in all users of __module_text

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241220174731.514432-16-bigeasy@linutronix.de>
Date: Fri, 20 Dec 2024 18:41:29 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-modules@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Daniel Gomez <da.gomez@...sung.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v2 15/28] module: Use RCU in all users of __module_text_address().

__module_text_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

Replace the preempt_disable() section around __module_text_address()
with RCU.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/module/main.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 80877741ac7e5..6a99076146cbc 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -823,13 +823,12 @@ void symbol_put_addr(void *addr)
 
 	/*
 	 * Even though we hold a reference on the module; we still need to
-	 * disable preemption in order to safely traverse the data structure.
+	 * RCU read section in order to safely traverse the data structure.
 	 */
-	preempt_disable();
+	guard(rcu)();
 	modaddr = __module_text_address(a);
 	BUG_ON(!modaddr);
 	module_put(modaddr);
-	preempt_enable();
 }
 EXPORT_SYMBOL_GPL(symbol_put_addr);
 
@@ -3694,20 +3693,15 @@ struct module *__module_address(unsigned long addr)
  */
 bool is_module_text_address(unsigned long addr)
 {
-	bool ret;
-
-	preempt_disable();
-	ret = __module_text_address(addr) != NULL;
-	preempt_enable();
-
-	return ret;
+	guard(rcu)();
+	return __module_text_address(addr) != NULL;
 }
 
 /**
  * __module_text_address() - get the module whose code contains an address.
  * @addr: the address.
  *
- * Must be called with preempt disabled or module mutex held so that
+ * Must be called within RCU read section or module mutex held so that
  * module doesn't get freed during this.
  */
 struct module *__module_text_address(unsigned long addr)
-- 
2.45.2