From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Longpeng(Mike)" Subject: [PATCH 2/2] crypto: virtio: fix an memory use-after-free bug Date: Mon, 25 May 2020 08:56:27 +0800 Message-ID: <20200525005627.707-3-longpeng2@huawei.com> References: <20200525005627.707-1-longpeng2@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <20200525005627.707-1-longpeng2@huawei.com> Sender: linux-crypto-owner@vger.kernel.org To: linux-crypto@vger.kernel.org Cc: "Longpeng(Mike)" , Gonglei , Herbert Xu , "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, LABBE Corentin List-Id: virtualization@lists.linuxfoundation.org The system'll crash when we insmod crypto/tcrypto.ko with mode=155. After dig into this case, I find it's caused by reuse the request memory. In crypto_authenc_init_tfm, we'll set the reqsize to: [PART 1]sizeof(authenc_request_ctx) + [PART 2]ictx->reqoff + [PART 3]MAX(ahash part, skcipher part) and the 'PART 3' will be used by both ahash and skcipher. When virtio_crypto driver finish skcipher req, it'll call ->complete callback(in crypto_finalize_skcipher_request) and then free its resources which pointers are recorded in 'skcipher parts'. However, the ->complete is 'crypto_authenc_encrypt_done' in this case, it will use the 'ahash part' of the request and change its content, so virtio_crypto driver will get the wrong pointer after ->complete finish and mistakenly free some other memory. So the system will crash at last when this memory be used again. We can free the resources before calling ->complete to fix this issue. Cc: Gonglei Cc: Herbert Xu Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: "David S. Miller" Cc: virtualization@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org Reported-by: LABBE Corentin Signed-off-by: Longpeng(Mike) --- drivers/crypto/virtio/virtio_crypto_algs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/crypto/virtio/virtio_crypto_algs.c b/drivers/crypto/virtio/virtio_crypto_algs.c index 2fa1129f96d6..3800356fb764 100644 --- a/drivers/crypto/virtio/virtio_crypto_algs.c +++ b/drivers/crypto/virtio/virtio_crypto_algs.c @@ -587,10 +587,11 @@ static void virtio_crypto_skcipher_finalize_req( scatterwalk_map_and_copy(req->iv, req->dst, req->cryptlen - AES_BLOCK_SIZE, AES_BLOCK_SIZE, 0); - crypto_finalize_skcipher_request(vc_sym_req->base.dataq->engine, - req, err); kzfree(vc_sym_req->iv); virtcrypto_clear_request(&vc_sym_req->base); + + crypto_finalize_skcipher_request(vc_sym_req->base.dataq->engine, + req, err); } static struct virtio_crypto_algo virtio_crypto_algs[] = { { -- 2.17.1