crypto: do not free algorithm before using

In multiple functions, the algorithm fields are read after its reference
is dropped through crypto_mod_put. In this case, the algorithm memory
may be freed, resulting in use-after-free bugs. This patch delays the
put operation until the algorithm is never used.

Fixes: 79c65d179a40 ("crypto: cbc - Convert to skcipher")
Fixes: a7d85e06ed80 ("crypto: cfb - add support for Cipher FeedBack mode")
Fixes: 043a44001b9e ("crypto: pcbc - Convert to skcipher")
Cc: <stable@vger.kernel.org>
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 4 insertions, 2 deletions

diff --git a/crypto/cfb.c b/crypto/cfb.c
index a0d68c09e1b9..20987d0e09d8 100644
--- a/crypto/cfb.c
+++ b/crypto/cfb.c
@@ -286,9 +286,8 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
         spawn = skcipher_instance_ctx(inst);
         err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
                                 CRYPTO_ALG_TYPE_MASK);
-        crypto_mod_put(alg);
         if (err)
-                goto err_free_inst;
+                goto err_put_alg;
 
         err = crypto_inst_setname(skcipher_crypto_instance(inst), "cfb", alg);
         if (err)
@@ -317,12 +316,15 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
         err = skcipher_register_instance(tmpl, inst);
         if (err)
                 goto err_drop_spawn;
+        crypto_mod_put(alg);
 
 out:
         return err;
 
 err_drop_spawn:
         crypto_drop_spawn(spawn);
+err_put_alg:
+        crypto_mod_put(alg);
 err_free_inst:
         kfree(inst);
         goto out;