crypto: cryptd - disable softirqs in cryptd_queue_worker to prevent data corruption

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

Cc: stable@vger.kernel.org
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>

1 files changed, 8 insertions, 3 deletions

diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index 671d4d6d14df..7bdd61b867c8 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;