crypto: user - fix use_after_free of struct xxx_request

All crypto_stats functions use the struct xxx_request for feeding stats,
but in some case this structure could already be freed.

For fixing this, the needed parameters (len and alg) will be stored
before the request being executed.
Fixes: cac5818c25d0 ("crypto: user - Implement a generic crypto statistics")
Reported-by: syzbot <syzbot+6939a606a5305e9e9799@syzkaller.appspotmail.com>

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 8 insertions, 28 deletions

diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h
index dff54731ddf4..480f8301a47d 100644
--- a/include/crypto/skcipher.h
+++ b/include/crypto/skcipher.h
@@ -486,32 +486,6 @@ static inline struct crypto_sync_skcipher *crypto_sync_skcipher_reqtfm(
 	return container_of(tfm, struct crypto_sync_skcipher, base);
 }
 
-static inline void crypto_stat_skcipher_encrypt(struct skcipher_request *req,
-						int ret, struct crypto_alg *alg)
-{
-#ifdef CONFIG_CRYPTO_STATS
-	if (ret && ret != -EINPROGRESS && ret != -EBUSY) {
-		atomic64_inc(&alg->cipher_err_cnt);
-	} else {
-		atomic64_inc(&alg->encrypt_cnt);
-		atomic64_add(req->cryptlen, &alg->encrypt_tlen);
-	}
-#endif
-}
-
-static inline void crypto_stat_skcipher_decrypt(struct skcipher_request *req,
-						int ret, struct crypto_alg *alg)
-{
-#ifdef CONFIG_CRYPTO_STATS
-	if (ret && ret != -EINPROGRESS && ret != -EBUSY) {
-		atomic64_inc(&alg->cipher_err_cnt);
-	} else {
-		atomic64_inc(&alg->decrypt_cnt);
-		atomic64_add(req->cryptlen, &alg->decrypt_tlen);
-	}
-#endif
-}
-
 /**
  * crypto_skcipher_encrypt() - encrypt plaintext
  * @req: reference to the skcipher_request handle that holds all information
@@ -526,13 +500,16 @@ static inline void crypto_stat_skcipher_decrypt(struct skcipher_request *req,
 static inline int crypto_skcipher_encrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_alg *alg = tfm->base.__crt_alg;
+	unsigned int cryptlen = req->cryptlen;
 	int ret;
 
+	crypto_stats_get(alg);
 	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		ret = -ENOKEY;
 	else
 		ret = tfm->encrypt(req);
-	crypto_stat_skcipher_encrypt(req, ret, tfm->base.__crt_alg);
+	crypto_stats_skcipher_encrypt(cryptlen, ret, alg);
 	return ret;
 }
 
@@ -550,13 +527,16 @@ static inline int crypto_skcipher_encrypt(struct skcipher_request *req)
 static inline int crypto_skcipher_decrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_alg *alg = tfm->base.__crt_alg;
+	unsigned int cryptlen = req->cryptlen;
 	int ret;
 
+	crypto_stats_get(alg);
 	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		ret = -ENOKEY;
 	else
 		ret = tfm->decrypt(req);
-	crypto_stat_skcipher_decrypt(req, ret, tfm->base.__crt_alg);
+	crypto_stats_skcipher_decrypt(cryptlen, ret, alg);
 	return ret;
 }