From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Shah Subject: [PATCH 1/2] hwrng: don't fetch rng from sources without init Date: Wed, 2 Jul 2014 15:58:15 +0530 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: In-Reply-To: References: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: linux-kernel@vger.kernel.org Cc: jason@lakedaemon.net, keescook@chromium.org, stable@vger.kernel.org, Virtualization List , Amit Shah , herbert@gondor.apana.org.au List-Id: virtualization@lists.linuxfoundation.org Commit d9e7972619334 "hwrng: add randomness to system from rng sources" added a call to rng_get_data() from the hwrng_register() function. However, some rng devices need initialization before data can be read from them. Also, the virtio-rng device does not behave properly when this call is made in its probe() routine - the virtio core sets the DRIVER_OK status bit only on a successful probe, which means the host ignores all communication from the guest, and the guest insmod or boot process just sits there doing nothing. This commit makes the call to rng_get_data() depend on no init fn pointer being registered by the device. If an init function is registered, this call isn't made. CC: Kees Cook CC: Jason Cooper CC: Herbert Xu CC: # For 3.15 only Signed-off-by: Amit Shah --- drivers/char/hw_random/core.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 334601c..3f3941d 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -347,9 +347,11 @@ int hwrng_register(struct hwrng *rng) INIT_LIST_HEAD(&rng->list); list_add_tail(&rng->list, &rng_list); - bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1); - if (bytes_read > 0) - add_device_randomness(bytes, bytes_read); + if (!rng->init) { + bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1); + if (bytes_read > 0) + add_device_randomness(bytes, bytes_read); + } out_unlock: mutex_unlock(&rng_mutex); out: -- 1.9.3