Messages in this thread Patch in this message | | | 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 |
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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 <arei.gonglei@huawei.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: virtualization@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org
Reported-by: LABBE Corentin <clabbe@baylibre.com> Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> --- 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
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