crypto: cryptd - disable softirqs in cryptd_queue_worker to prevent data corruption
Jussi Kivilinna [Sun, 21 Oct 2012 17:42:28 +0000 (20:42 +0300)]
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@gmail.com>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

crypto/cryptd.c

index 671d4d6..7bdd61b 100644 (file)
@@ -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;