From 24c65bc7037e7d0f362c0df70d17dd72ee64b8b9 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Fri, 31 Oct 2014 07:50:11 +0100 Subject: hwrng: pseries - port to new read API and fix stack corruption The add_early_randomness() function in drivers/char/hw_random/core.c passes a 16-byte buffer to pseries_rng_data_read(). Unfortunately, plpar_hcall() returns four 64-bit values and trashes 16 bytes on the stack. This bug has been lying around for a long time. It got unveiled by: commit d3cc7996473a7bdd33256029988ea690754e4e2a Author: Amit Shah Date: Thu Jul 10 15:42:34 2014 +0530 hwrng: fetch randomness only after device init It may trig a oops while loading or unloading the pseries-rng module for both PowerVM and PowerKVM guests. This patch does two things: - pass an intermediate well sized buffer to plpar_hcall(). This is acceptalbe since we're not on a hot path. - move to the new read API so that we know the return buffer size for sure. Cc: stable@vger.kernel.org Signed-off-by: Greg Kurz Signed-off-by: Herbert Xu --- drivers/char/hw_random/pseries-rng.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/hw_random/pseries-rng.c b/drivers/char/hw_random/pseries-rng.c index 6226aa08c36a..bcf86f91800a 100644 --- a/drivers/char/hw_random/pseries-rng.c +++ b/drivers/char/hw_random/pseries-rng.c @@ -25,18 +25,21 @@ #include -static int pseries_rng_data_read(struct hwrng *rng, u32 *data) +static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) { + u64 buffer[PLPAR_HCALL_BUFSIZE]; + size_t size = max < 8 ? max : 8; int rc; - rc = plpar_hcall(H_RANDOM, (unsigned long *)data); + rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer); if (rc != H_SUCCESS) { pr_err_ratelimited("H_RANDOM call failed %d\n", rc); return -EIO; } + memcpy(data, buffer, size); /* The hypervisor interface returns 64 bits */ - return 8; + return size; } /** @@ -55,7 +58,7 @@ static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev) static struct hwrng pseries_rng = { .name = KBUILD_MODNAME, - .data_read = pseries_rng_data_read, + .read = pseries_rng_read, }; static int __init pseries_rng_probe(struct vio_dev *dev, -- cgit v1.2.3 From 65eca3a20264a8999570c269406196bd1ae23be7 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Mon, 20 Oct 2014 15:58:49 +0200 Subject: virtio_console: move early VQ enablement Commit f5866db6 (virtio_console: enable VQs early) tried to make sure that DRIVER_OK was set when virtio_console started using its virtqueues. Doing this in add_port(), however, means that we try to set DRIVER_OK again when when a port is dynamically added after the probe function is done. Let's move virtio_device_ready() to the probe function just before trying to use the virtqueues instead. This is fine as nothing can fail inbetween. Reported-by: Thomas Graf Reviewed-by: Michael S. Tsirkin Signed-off-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin --- drivers/char/virtio_console.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index bfa640023e64..cf7a561fad7c 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1449,8 +1449,6 @@ static int add_port(struct ports_device *portdev, u32 id) spin_lock_init(&port->outvq_lock); init_waitqueue_head(&port->waitqueue); - virtio_device_ready(portdev->vdev); - /* Fill the in_vq with buffers so the host can send us data. */ nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); if (!nr_added_bufs) { @@ -2026,6 +2024,8 @@ static int virtcons_probe(struct virtio_device *vdev) spin_lock_init(&portdev->ports_lock); INIT_LIST_HEAD(&portdev->ports); + virtio_device_ready(portdev->vdev); + if (multiport) { unsigned int nr_added_bufs; -- cgit v1.2.3