crypto: af_alg - fix race accessing cipher request

When invoking an asynchronous cipher operation, the invocation of the
callback may be performed before the subsequent operations in the
initial code path are invoked. The callback deletes the cipher request
data structure which implies that after the invocation of the
asynchronous cipher operation, this data structure must not be accessed
any more.

The setting of the return code size with the request data structure must
therefore be moved before the invocation of the asynchronous cipher
operation.

Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management")
Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management")
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index c8a32bef208a657056ccf81e1c60a7e79f87720a..b73db2b27656f7c371ec07d5bbd7f66c8c274eb1 100644 (file)
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -291,6 +291,10 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
                /* AIO operation */
                sock_hold(sk);
                areq->iocb = msg->msg_iocb;
+
+               /* Remember output size that will be generated. */
+               areq->outlen = outlen;
+
                aead_request_set_callback(&areq->cra_u.aead_req,
                                          CRYPTO_TFM_REQ_MAY_BACKLOG,
                                          af_alg_async_cb, areq);
@@ -298,12 +302,8 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
                                 crypto_aead_decrypt(&areq->cra_u.aead_req);
 
                /* AIO operation in progress */
-               if (err == -EINPROGRESS || err == -EBUSY) {
-                       /* Remember output size that will be generated. */
-                       areq->outlen = outlen;
-
+               if (err == -EINPROGRESS || err == -EBUSY)
                        return -EIOCBQUEUED;
-               }
 
                sock_put(sk);
        } else {

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 6fb595cd63ac2a9d14fd606210eeb065930e3724..baef9bfccddaa94728bea5933bea16c32b2a32b5 100644 (file)
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -125,6 +125,10 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
                /* AIO operation */
                sock_hold(sk);
                areq->iocb = msg->msg_iocb;
+
+               /* Remember output size that will be generated. */
+               areq->outlen = len;
+
                skcipher_request_set_callback(&areq->cra_u.skcipher_req,
                                              CRYPTO_TFM_REQ_MAY_SLEEP,
                                              af_alg_async_cb, areq);
@@ -133,12 +137,8 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
                        crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
 
                /* AIO operation in progress */
-               if (err == -EINPROGRESS || err == -EBUSY) {
-                       /* Remember output size that will be generated. */
-                       areq->outlen = len;
-
+               if (err == -EINPROGRESS || err == -EBUSY)
                        return -EIOCBQUEUED;
-               }
 
                sock_put(sk);
        } else {