[patch 21/36] CRYPTO api: Fix potential race in crypto_remove_spawn

[Greg KH <gregkh@suse.de>]

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2.6.22-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Herbert Xu <herbert@gondor.apana.org.au>

[CRYPTO] api: Fix potential race in crypto_remove_spawn

[ Upstream commit: 38cb2419f544ad413c7f7aa8c17fd7377610cdd8 ]

As it is crypto_remove_spawn may try to unregister an instance which is
yet to be registered.  This patch fixes this by checking whether the
instance has been registered before attempting to remove it.

It also removes a bogus cra_destroy check in crypto_register_instance as
1) it's outside the mutex;
2) we have a check in __crypto_register_alg already.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 crypto/algapi.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -98,6 +98,9 @@ static void crypto_remove_spawn(struct c
 		return;
 
 	inst->alg.cra_flags |= CRYPTO_ALG_DEAD;
+	if (hlist_unhashed(&inst->list))
+		return;
+
 	if (!tmpl || !crypto_tmpl_get(tmpl))
 		return;
 
@@ -333,9 +336,6 @@ int crypto_register_instance(struct cryp
 	LIST_HEAD(list);
 	int err = -EINVAL;
 
-	if (inst->alg.cra_destroy)
-		goto err;
-
 	err = crypto_check_alg(&inst->alg);
 	if (err)
 		goto err;

--