[PATCH v2] crypto: pcrypt: Fix possible deadlock in padata_sysfs_release

[Kefeng Wang]

There is a deadlock issue in pcrypt_init_padata(),

pcrypt_init_padata()
    cpus_read_lock()
      padata_free()
        padata_sysfs_release()
          cpus_read_lock()

Narrow rcu_read_lock/unlock() and move put_online_cpus()
before padata_free() to fix it.

Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.w...@huawei.com>
---
 crypto/pcrypt.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/crypto/pcrypt.c b/crypto/pcrypt.c
index 0e9ce329fd47..f3dacb714cd4 100644
--- a/crypto/pcrypt.c
+++ b/crypto/pcrypt.c
@@ -407,16 +407,19 @@ static int pcrypt_init_padata(struct padata_pcrypt 
*pcrypt,
        int ret = -ENOMEM;
        struct pcrypt_cpumask *mask;
 
-       get_online_cpus();
 
        pcrypt->wq = alloc_workqueue("%s", WQ_MEM_RECLAIM | WQ_CPU_INTENSIVE,
                                     1, name);
        if (!pcrypt->wq)
                goto err;
 
+       get_online_cpus();
+
        pcrypt->pinst = padata_alloc_possible(pcrypt->wq);
-       if (!pcrypt->pinst)
+       if (!pcrypt->pinst) {
+               put_online_cpus();
                goto err_destroy_workqueue;
+       }
 
        mask = kmalloc(sizeof(*mask), GFP_KERNEL);
        if (!mask)
@@ -448,12 +451,11 @@ static int pcrypt_init_padata(struct padata_pcrypt 
*pcrypt,
        free_cpumask_var(mask->mask);
        kfree(mask);
 err_free_padata:
+       put_online_cpus();
        padata_free(pcrypt->pinst);
 err_destroy_workqueue:
        destroy_workqueue(pcrypt->wq);
 err:
-       put_online_cpus();
-
        return ret;
 }
 
-- 
2.20.1