crypto: algif_aead - Fix bogus request dereference in completion func…

…tion

commit e6534aebb26e32fbab14df9c713c65e8507d17e4 upstream.

The algif_aead completion function tries to deduce the aead_request
from the crypto_async_request argument.  This is broken because
the API does not guarantee that the same request will be pased to
the completion function.  Only the value of req->data can be used
in the completion function.

This patch fixes it by storing a pointer to sk in areq and using
that instead of passing in sk through req->data.

Fixes: 83094e5 ("crypto: af_alg - add async support to...")
Signed-off-by: Herbert Xu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

crypto/algif_aead.c

@@ -39,6 +39,7 @@ struct aead_async_req {
  struct aead_async_rsgl first_rsgl;
  struct list_head list;
  struct kiocb *iocb;
+ struct sock *sk;
  unsigned int tsgls;
  char iv[];
 };
@@ -379,12 +380,10 @@ static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 
 static void aead_async_cb(struct crypto_async_request *_req, int err)
 {
- struct sock *sk = _req->data;
- struct alg_sock *ask = alg_sk(sk);
- struct aead_ctx *ctx = ask->private;
- struct crypto_aead *tfm = crypto_aead_reqtfm(&ctx->aead_req);
- struct aead_request *req = aead_request_cast(_req);
+ struct aead_request *req = _req->data;
+ struct crypto_aead *tfm = crypto_aead_reqtfm(req);
  struct aead_async_req *areq = GET_ASYM_REQ(req, tfm);
+ struct sock *sk = areq->sk;
  struct scatterlist *sg = areq->tsgl;
  struct aead_async_rsgl *rsgl;
  struct kiocb *iocb = areq->iocb;
@@ -447,11 +446,12 @@ static int aead_recvmsg_async(struct socket *sock, struct msghdr *msg,
  memset(&areq->first_rsgl, '\0', sizeof(areq->first_rsgl));
  INIT_LIST_HEAD(&areq->list);
  areq->iocb = msg->msg_iocb;
+ areq->sk = sk;
  memcpy(areq->iv, ctx->iv, crypto_aead_ivsize(tfm));
  aead_request_set_tfm(req, tfm);
  aead_request_set_ad(req, ctx->aead_assoclen);
  aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
- aead_async_cb, sk);
+ aead_async_cb, req);
  used -= ctx->aead_assoclen;
 
  /* take over all tx sgls from ctx */