From: Vincent Whitchurch vincent.whitchurch@axis.com
[ Upstream commit b503de239f62eca898cfb7e820d9a35499137d22 ]
The driver currently assumes that the notify callback is only received when the device is done with all the queued buffers.
However, this is not true, since the notify callback could be called without any of the queued buffers being completed (for example, with virtio-pci and shared interrupts) or with only some of the buffers being completed (since the driver makes them available to the device in multiple separate virtqueue_add_sgs() calls).
This can lead to incorrect data on the I2C bus or memory corruption in the guest if the device operates on buffers which are have been freed by the driver. (The WARN_ON in the driver is also triggered.)
BUG kmalloc-128 (Tainted: G W ): Poison overwritten First byte 0x0 instead of 0x6b Allocated in i2cdev_ioctl_rdwr+0x9d/0x1de age=243 cpu=0 pid=28 memdup_user+0x2e/0xbd i2cdev_ioctl_rdwr+0x9d/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 Freed in i2cdev_ioctl_rdwr+0x1bb/0x1de age=68 cpu=0 pid=28 kfree+0x1bd/0x1cc i2cdev_ioctl_rdwr+0x1bb/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41
Fix this by calling virtio_get_buf() from the notify handler like other virtio drivers and by actually waiting for all the buffers to be completed.
Fixes: 3cfc88380413d20f ("i2c: virtio: add a virtio i2c frontend driver") Acked-by: Viresh Kumar viresh.kumar@linaro.org Signed-off-by: Vincent Whitchurch vincent.whitchurch@axis.com Acked-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: Wolfram Sang wsa@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-virtio.c | 32 ++++++++++++-------------------- 1 file changed, 12 insertions(+), 20 deletions(-)
diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c index 7b2474e6876f4..5cb21d7da05b6 100644 --- a/drivers/i2c/busses/i2c-virtio.c +++ b/drivers/i2c/busses/i2c-virtio.c @@ -22,24 +22,24 @@ /** * struct virtio_i2c - virtio I2C data * @vdev: virtio device for this controller - * @completion: completion of virtio I2C message * @adap: I2C adapter for this controller * @vq: the virtio virtqueue for communication */ struct virtio_i2c { struct virtio_device *vdev; - struct completion completion; struct i2c_adapter adap; struct virtqueue *vq; };
/** * struct virtio_i2c_req - the virtio I2C request structure + * @completion: completion of virtio I2C message * @out_hdr: the OUT header of the virtio I2C message * @buf: the buffer into which data is read, or from which it's written * @in_hdr: the IN header of the virtio I2C message */ struct virtio_i2c_req { + struct completion completion; struct virtio_i2c_out_hdr out_hdr ____cacheline_aligned; uint8_t *buf ____cacheline_aligned; struct virtio_i2c_in_hdr in_hdr ____cacheline_aligned; @@ -47,9 +47,11 @@ struct virtio_i2c_req {
static void virtio_i2c_msg_done(struct virtqueue *vq) { - struct virtio_i2c *vi = vq->vdev->priv; + struct virtio_i2c_req *req; + unsigned int len;
- complete(&vi->completion); + while ((req = virtqueue_get_buf(vq, &len))) + complete(&req->completion); }
static int virtio_i2c_prepare_reqs(struct virtqueue *vq, @@ -62,6 +64,8 @@ static int virtio_i2c_prepare_reqs(struct virtqueue *vq, for (i = 0; i < num; i++) { int outcnt = 0, incnt = 0;
+ init_completion(&reqs[i].completion); + /* * We don't support 0 length messages and so filter out * 0 length transfers by using i2c_adapter_quirks. @@ -108,21 +112,15 @@ static int virtio_i2c_complete_reqs(struct virtqueue *vq, struct virtio_i2c_req *reqs, struct i2c_msg *msgs, int num) { - struct virtio_i2c_req *req; bool failed = false; - unsigned int len; int i, j = 0;
for (i = 0; i < num; i++) { - /* Detach the ith request from the vq */ - req = virtqueue_get_buf(vq, &len); + struct virtio_i2c_req *req = &reqs[i];
- /* - * Condition req == &reqs[i] should always meet since we have - * total num requests in the vq. reqs[i] can never be NULL here. - */ - if (!failed && (WARN_ON(req != &reqs[i]) || - req->in_hdr.status != VIRTIO_I2C_MSG_OK)) + wait_for_completion(&req->completion); + + if (!failed && req->in_hdr.status != VIRTIO_I2C_MSG_OK) failed = true;
i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], !failed); @@ -158,12 +156,8 @@ static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, * remote here to clear the virtqueue, so we can try another set of * messages later on. */ - - reinit_completion(&vi->completion); virtqueue_kick(vq);
- wait_for_completion(&vi->completion); - count = virtio_i2c_complete_reqs(vq, reqs, msgs, count);
err_free: @@ -211,8 +205,6 @@ static int virtio_i2c_probe(struct virtio_device *vdev) vdev->priv = vi; vi->vdev = vdev;
- init_completion(&vi->completion); - ret = virtio_i2c_setup_vqs(vi); if (ret) return ret;