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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jon Maloy <jmaloy@redhat.com>,
        Tuong Lien <tuong.t.lien@dektech.com.au>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.8 14/16] tipc: fix using smp_processor_id() in preemptible
Date:   Fri, 11 Sep 2020 14:47:31 +0200
Message-Id: <20200911122500.284435224@linuxfoundation.org>
In-Reply-To: <20200911122459.585735377@linuxfoundation.org>
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From: Tuong Lien <tuong.t.lien@dektech.com.au>

[ Upstream commit bb8872a1e6bc911869a729240781076ed950764b ]

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@redhat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/tipc/crypto.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -326,7 +326,8 @@ static void tipc_aead_free(struct rcu_he
 	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 t
  */
 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;
 }
 
 /**