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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2022-05-04 18:07:36 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2022-05-13 12:24:48 +0300
commit91e8bcd7b4da182e09ea19a2c73167345fe14c98 (patch)
tree6fa3579beb11a36d64b34a178cf992a9c5ef9e6c
parent42a01af3f13f09656af1f97d58e98415242eef45 (diff)
downloadlinux-91e8bcd7b4da182e09ea19a2c73167345fe14c98.tar.xz
crypto: cryptd - Protect per-CPU resource by disabling BH.
The access to cryptd_queue::cpu_queue is synchronized by disabling preemption in cryptd_enqueue_request() and disabling BH in cryptd_queue_worker(). This implies that access is allowed from BH. If cryptd_enqueue_request() is invoked from preemptible context _and_ soft interrupt then this can lead to list corruption since cryptd_enqueue_request() is not protected against access from soft interrupt. Replace get_cpu() in cryptd_enqueue_request() with local_bh_disable() to ensure BH is always disabled. Remove preempt_disable() from cryptd_queue_worker() since it is not needed because local_bh_disable() ensures synchronisation. Fixes: 254eff771441 ("crypto: cryptd - Per-CPU thread implementation...") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
-rw-r--r--crypto/cryptd.c23
1 files changed, 11 insertions, 12 deletions
diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index a1bea0f4baa8..668095eca0fa 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -39,6 +39,10 @@ struct cryptd_cpu_queue {
};
struct cryptd_queue {
+ /*
+ * Protected by disabling BH to allow enqueueing from softinterrupt and
+ * dequeuing from kworker (cryptd_queue_worker()).
+ */
struct cryptd_cpu_queue __percpu *cpu_queue;
};
@@ -125,28 +129,28 @@ static void cryptd_fini_queue(struct cryptd_queue *queue)
static int cryptd_enqueue_request(struct cryptd_queue *queue,
struct crypto_async_request *request)
{
- int cpu, err;
+ int err;
struct cryptd_cpu_queue *cpu_queue;
refcount_t *refcnt;
- cpu = get_cpu();
+ local_bh_disable();
cpu_queue = this_cpu_ptr(queue->cpu_queue);
err = crypto_enqueue_request(&cpu_queue->queue, request);
refcnt = crypto_tfm_ctx(request->tfm);
if (err == -ENOSPC)
- goto out_put_cpu;
+ goto out;
- queue_work_on(cpu, cryptd_wq, &cpu_queue->work);
+ queue_work_on(smp_processor_id(), cryptd_wq, &cpu_queue->work);
if (!refcount_read(refcnt))
- goto out_put_cpu;
+ goto out;
refcount_inc(refcnt);
-out_put_cpu:
- put_cpu();
+out:
+ local_bh_enable();
return err;
}
@@ -162,15 +166,10 @@ static void cryptd_queue_worker(struct work_struct *work)
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(). 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)