linux-kernel - [PATCH 2/2] cryptd: Use nested-BH locking for cryptd_cpu

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20250514110750.852919-3-bigeasy@linutronix.de>
Date: Wed, 14 May 2025 13:07:50 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-kernel@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev
Cc: tglx@...utronix.de,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	"David S. Miller" <davem@...emloft.net>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	linux-crypto@...r.kernel.org
Subject: [PATCH 2/2] cryptd: Use nested-BH locking for cryptd_cpu_queue

cryptd_queue::cryptd_cpu_queue is a per-CPU variable and relies on
disabled BH for its locking. Without per-CPU locking in
local_bh_disable() on PREEMPT_RT this data structure requires explicit
locking.

Add a local_lock_t to the struct cryptd_cpu_queue and use
local_lock_nested_bh() for locking. This change adds only lockdep
coverage and does not alter the functional behaviour for !PREEMPT_RT.

Cc: "David S. Miller" <davem@...emloft.net>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: linux-crypto@...r.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 crypto/cryptd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index 31d022d47f7a0..39c9e83a3a5b8 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -34,6 +34,7 @@ MODULE_PARM_DESC(cryptd_max_cpu_qlen, "Set cryptd Max queue depth");
 static struct workqueue_struct *cryptd_wq;
 
 struct cryptd_cpu_queue {
+	local_lock_t bh_lock;
 	struct crypto_queue queue;
 	struct work_struct work;
 };
@@ -110,6 +111,7 @@ static int cryptd_init_queue(struct cryptd_queue *queue,
 		cpu_queue = per_cpu_ptr(queue->cpu_queue, cpu);
 		crypto_init_queue(&cpu_queue->queue, max_cpu_qlen);
 		INIT_WORK(&cpu_queue->work, cryptd_queue_worker);
+		local_lock_init(&cpu_queue->bh_lock);
 	}
 	pr_info("cryptd: max_cpu_qlen set to %d\n", max_cpu_qlen);
 	return 0;
@@ -135,6 +137,7 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
 	refcount_t *refcnt;
 
 	local_bh_disable();
+	local_lock_nested_bh(&queue->cpu_queue->bh_lock);
 	cpu_queue = this_cpu_ptr(queue->cpu_queue);
 	err = crypto_enqueue_request(&cpu_queue->queue, request);
 
@@ -151,6 +154,7 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
 	refcount_inc(refcnt);
 
 out:
+	local_unlock_nested_bh(&queue->cpu_queue->bh_lock);
 	local_bh_enable();
 
 	return err;
@@ -169,8 +173,10 @@ static void cryptd_queue_worker(struct work_struct *work)
 	 * Only handle one request at a time to avoid hogging crypto workqueue.
 	 */
 	local_bh_disable();
+	__local_lock_nested_bh(&cpu_queue->bh_lock);
 	backlog = crypto_get_backlog(&cpu_queue->queue);
 	req = crypto_dequeue_request(&cpu_queue->queue);
+	__local_unlock_nested_bh(&cpu_queue->bh_lock);
 	local_bh_enable();
 
 	if (!req)
-- 
2.49.0