On Tuesday 27 May 2008 00:25:28 Christian Borntraeger wrote:
> If virtio_rng is build as a module, random_data is an address in vmalloc
> space. As virtio expects guest real addresses, this can cause any kind of
> funny behaviour, so lets allocate random_data dynamically with kmalloc.
>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Erk, nasty trap...
> - sg_init_one(&sg, &random_data, sizeof(random_data));
> + sg_init_one(&sg, random_data, 64);
Constant in two places, I've moved to a #define.
> static int __init init(void)
> {
> + random_data = kmalloc(64, GFP_KERNEL);
> + if (!random_data)
> + return -ENOMEM;
> return register_virtio_driver(&virtio_rng);
And added cleanup on register_virtio_driver fail (a tiny leak. but still).
Cheers,
Rusty.
Subject: virtio_rng: dont use vmalloced addresses for virtio
Date: Mon, 26 May 2008 16:25:28 +0200
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
If virtio_rng is build as a module, random_data is an address in vmalloc
space. As virtio expects guest real addresses, this can cause any kind of
funny behaviour, so lets allocate random_data dynamically with kmalloc.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
drivers/char/hw_random/virtio-rng.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff -r 82ce499b3321 drivers/char/hw_random/virtio-rng.c
--- a/drivers/char/hw_random/virtio-rng.c Tue May 27 11:22:18 2008 +1000
+++ b/drivers/char/hw_random/virtio-rng.c Tue May 27 11:25:32 2008 +1000
@@ -26,8 +26,10 @@
/* The host will fill any buffer we give it with sweet, sweet randomness. We
* give it 64 bytes at a time, and the hwrng framework takes it 4 bytes at a
* time. */
+#define RANDOM_DATA_SIZE 64
+
static struct virtqueue *vq;
-static u32 random_data[16];
+static u32 *random_data;
static unsigned int data_left;
static DECLARE_COMPLETION(have_data);
@@ -47,9 +49,9 @@ static void register_buffer(void)
{
struct scatterlist sg;
- sg_init_one(&sg, &random_data, sizeof(random_data));
+ sg_init_one(&sg, random_data, RANDOM_DATA_SIZE);
/* There should always be room for one buffer. */
- if (vq->vq_ops->add_buf(vq, &sg, 0, 1, &random_data) != 0)
+ if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) != 0)
BUG();
vq->vq_ops->kick(vq);
}
@@ -128,11 +130,21 @@ static struct virtio_driver virtio_rng =
static int __init init(void)
{
- return register_virtio_driver(&virtio_rng);
+ int err;
+
+ random_data = kmalloc(RANDOM_DATA_SIZE, GFP_KERNEL);
+ if (!random_data)
+ return -ENOMEM;
+
+ err = register_virtio_driver(&virtio_rng);
+ if (err)
+ kfree(random_data);
+ return err;
}
static void __exit fini(void)
{
+ kfree(random_data);
unregister_virtio_driver(&virtio_rng);
}
module_init(init);
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