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crypto: af_alg - remove locking in async callback

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The code paths protected by the socket-lock do not use or modify the
socket in a non-atomic fashion. The actions pertaining the socket do not
even need to be handled as an atomic operation. Thus, the socket-lock
can be safely ignored.

This fixes a bug regarding scheduling in atomic as the callback function
may be invoked in interrupt context.

In addition, the sock_hold is moved before the AIO encrypt/decrypt
operation to ensure that the socket is always present. This avoids a
tiny race window where the socket is unprotected and yet used by the AIO
operation.

Finally, the release of resources for a crypto operation is moved into a
common function of af_alg_free_resources.

Cc: <stable@vger.kernel.org>
Fixes: e870456d8e ("crypto: algif_skcipher - overhaul memory management")
Fixes: d887c52d6a ("crypto: algif_aead - overhaul memory management")
Reported-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Tested-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller
2017-11-10 13:20:55 +01:00
committed by Herbert Xu
parent 8e1fa89aa8
commit 7d2c3f54e6
4 changed files with 39 additions and 29 deletions
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21
crypto/af_alg.c
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@@ -1020,6 +1020,18 @@ unlock:
}
EXPORT_SYMBOL_GPL(af_alg_sendpage);
/**
* af_alg_free_resources - release resources required for crypto request
*/
void af_alg_free_resources(struct af_alg_async_req *areq)
{
struct sock *sk = areq->sk;
af_alg_free_areq_sgls(areq);
sock_kfree_s(sk, areq, areq->areqlen);
}
EXPORT_SYMBOL_GPL(af_alg_free_resources);
/**
* af_alg_async_cb - AIO callback handler
*
@@ -1036,18 +1048,13 @@ void af_alg_async_cb(struct crypto_async_request *_req, int err)
struct kiocb *iocb = areq->iocb;
unsigned int resultlen;
lock_sock(sk);
/* Buffer size written by crypto operation. */
resultlen = areq->outlen;
af_alg_free_areq_sgls(areq);
sock_kfree_s(sk, areq, areq->areqlen);
__sock_put(sk);
af_alg_free_resources(areq);
sock_put(sk);
iocb->ki_complete(iocb, err ? err : resultlen, 0);
release_sock(sk);
}
EXPORT_SYMBOL_GPL(af_alg_async_cb);