1 files changed, 44 insertions, 2 deletions

diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
index 1ad33e555805..52f577a3868d 100644
--- a/lib/crc-t10dif.c
+++ b/lib/crc-t10dif.c
@@ -14,10 +14,47 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <crypto/hash.h>
+#include <crypto/algapi.h>
 #include <linux/static_key.h>
+#include <linux/notifier.h>
 
-static struct crypto_shash *crct10dif_tfm;
+static struct crypto_shash __rcu *crct10dif_tfm;
 static struct static_key crct10dif_fallback __read_mostly;
+DEFINE_MUTEX(crc_t10dif_mutex);
+
+static int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data)
+{
+	struct crypto_alg *alg = data;
+	struct crypto_shash *new, *old;
+
+	if (val != CRYPTO_MSG_ALG_LOADED ||
+	    static_key_false(&crct10dif_fallback) ||
+	    strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
+		return 0;
+
+	mutex_lock(&crc_t10dif_mutex);
+	old = rcu_dereference_protected(crct10dif_tfm,
+					lockdep_is_held(&crc_t10dif_mutex));
+	if (!old) {
+		mutex_unlock(&crc_t10dif_mutex);
+		return 0;
+	}
+	new = crypto_alloc_shash("crct10dif", 0, 0);
+	if (IS_ERR(new)) {
+		mutex_unlock(&crc_t10dif_mutex);
+		return 0;
+	}
+	rcu_assign_pointer(crct10dif_tfm, new);
+	mutex_unlock(&crc_t10dif_mutex);
+
+	synchronize_rcu();
+	crypto_free_shash(old);
+	return 0;
+}
+
+static struct notifier_block crc_t10dif_nb = {
+	.notifier_call = crc_t10dif_rehash,
+};
 
 __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
 {
@@ -30,11 +67,14 @@ __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
 	if (static_key_false(&crct10dif_fallback))
 		return crc_t10dif_generic(crc, buffer, len);
 
-	desc.shash.tfm = crct10dif_tfm;
+	rcu_read_lock();
+	desc.shash.tfm = rcu_dereference(crct10dif_tfm);
 	desc.shash.flags = 0;
 	*(__u16 *)desc.ctx = crc;
 
 	err = crypto_shash_update(&desc.shash, buffer, len);
+	rcu_read_unlock();
+
 	BUG_ON(err);
 
 	return *(__u16 *)desc.ctx;
@@ -49,6 +89,7 @@ EXPORT_SYMBOL(crc_t10dif);
 
 static int __init crc_t10dif_mod_init(void)
 {
+	crypto_register_notifier(&crc_t10dif_nb);
 	crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
 	if (IS_ERR(crct10dif_tfm)) {
 		static_key_slow_inc(&crct10dif_fallback);
@@ -59,6 +100,7 @@ static int __init crc_t10dif_mod_init(void)
 
 static void __exit crc_t10dif_mod_fini(void)
 {
+	crypto_unregister_notifier(&crc_t10dif_nb);
 	crypto_free_shash(crct10dif_tfm);
 }