netdev - [net] tipc: fix using smp_processor

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Date:   Sun, 30 Aug 2020 02:37:55 +0700
From:   Tuong Lien <tuong.t.lien@...tech.com.au>
To:     davem@...emloft.net, jmaloy@...hat.com, maloy@...jonn.com,
        ying.xue@...driver.com, netdev@...r.kernel.org
Cc:     tipc-discussion@...ts.sourceforge.net
Subject: [net] tipc: fix using smp_processor_id() in preemptible

The 'this_cpu_ptr()' is used to obtain the AEAD key' TFM on the current
CPU for encryption, however the execution can be preemptible since it's
actually user-space context, so the 'using smp_processor_id() in
preemptible' has been observed.

We fix the issue by using the 'get/put_cpu_ptr()' API which consists of
a 'preempt_disable()' instead.

Fixes: fc1b6d6de220 ("tipc: introduce TIPC encryption & authentication")
Acked-by: Jon Maloy <jmaloy@...hat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@...tech.com.au>
---
 net/tipc/crypto.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index c38babaa4e57..7c523dc81575 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -326,7 +326,8 @@ static void tipc_aead_free(struct rcu_head *rp)
 	if (aead->cloned) {
 		tipc_aead_put(aead->cloned);
 	} else {
-		head = *this_cpu_ptr(aead->tfm_entry);
+		head = *get_cpu_ptr(aead->tfm_entry);
+		put_cpu_ptr(aead->tfm_entry);
 		list_for_each_entry_safe(tfm_entry, tmp, &head->list, list) {
 			crypto_free_aead(tfm_entry->tfm);
 			list_del(&tfm_entry->list);
@@ -399,10 +400,15 @@ static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val)
  */
 static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead)
 {
-	struct tipc_tfm **tfm_entry = this_cpu_ptr(aead->tfm_entry);
+	struct tipc_tfm **tfm_entry;
+	struct crypto_aead *tfm;
 
+	tfm_entry = get_cpu_ptr(aead->tfm_entry);
 	*tfm_entry = list_next_entry(*tfm_entry, list);
-	return (*tfm_entry)->tfm;
+	tfm = (*tfm_entry)->tfm;
+	put_cpu_ptr(tfm_entry);
+
+	return tfm;
 }
 
 /**
-- 
2.26.2