linux-kernel - [ 22/82] crypto: cryptd - disable softirqs in cryptd_queue

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Message-Id: <20121114053936.947604243@decadent.org.uk>
Date:	Wed, 14 Nov 2012 05:39:55 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Jussi Kivilinna <jussi.kivilinna@...et.fi>,
	Gurucharan Shetty <gurucharan.shetty@...il.com>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: [ 22/82] crypto: cryptd - disable softirqs in cryptd_queue_worker to prevent
 data corruption

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jussi Kivilinna <jussi.kivilinna@...et.fi>

commit 9efade1b3e981f5064f9db9ca971b4dc7557ae42 upstream.

cryptd_queue_worker attempts to prevent simultaneous accesses to crypto
workqueue by cryptd_enqueue_request using preempt_disable/preempt_enable.
However cryptd_enqueue_request might be called from softirq context,
so add local_bh_disable/local_bh_enable to prevent data corruption and
panics.

Bug report at http://marc.info/?l=linux-crypto-vger&m=134858649616319&w=2

v2:
 - Disable software interrupts instead of hardware interrupts

Reported-by: Gurucharan Shetty <gurucharan.shetty@...il.com>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@...et.fi>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 crypto/cryptd.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index 671d4d6..7bdd61b 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -137,13 +137,18 @@ static void cryptd_queue_worker(struct work_struct *work)
 	struct crypto_async_request *req, *backlog;
 
 	cpu_queue = container_of(work, struct cryptd_cpu_queue, work);
-	/* Only handle one request at a time to avoid hogging crypto
-	 * workqueue. preempt_disable/enable is used to prevent
-	 * being preempted by cryptd_enqueue_request() */
+	/*
+	 * Only handle one request at a time to avoid hogging crypto workqueue.
+	 * preempt_disable/enable is used to prevent being preempted by
+	 * cryptd_enqueue_request(). local_bh_disable/enable is used to prevent
+	 * cryptd_enqueue_request() being accessed from software interrupts.
+	 */
+	local_bh_disable();
 	preempt_disable();
 	backlog = crypto_get_backlog(&cpu_queue->queue);
 	req = crypto_dequeue_request(&cpu_queue->queue);
 	preempt_enable();
+	local_bh_enable();
 
 	if (!req)
 		return;


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