crypto: fix broken crypto_register_instance() module handling

Commit 9c521a200bc3 ("crypto: api - remove instance when test failed")
tried to grab a module reference count before the module was even set.

Worse, it then goes on to free the module reference count after it is
set so you quickly end up with a negative module reference count which
prevents people from using any instances belonging to that module.

This patch moves the module initialisation before the reference
count.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 2d0a1c6..d2627a3 100644 (file)
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -525,12 +525,12 @@ int crypto_register_instance(struct crypto_template *tmpl,
        if (err)
                return err;
 
-       if (unlikely(!crypto_mod_get(&inst->alg)))
-               return -EAGAIN;
-
        inst->alg.cra_module = tmpl->module;
        inst->alg.cra_flags |= CRYPTO_ALG_INSTANCE;
 
+       if (unlikely(!crypto_mod_get(&inst->alg)))
+               return -EAGAIN;
+
        down_write(&crypto_alg_sem);
 
        larval = __crypto_register_alg(&inst->alg);