> From: gregkh@xxxxxxxxxxxxxxxxxxx <gregkh@xxxxxxxxxxxxxxxxxxx>
> Sent: Sunday, January 27, 2019 7:43 AM
> To: Dexuan Cui <decui@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx>;
> sashal@xxxxxxxxxx; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Subject: FAILED: patch "[PATCH] Drivers: hv: vmbus: Check for ring when
> getting debug info" failed to apply to 4.4-stable tree
>
>
> The patch below does not apply to the 4.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From ba50bf1ce9a51fc97db58b96d01306aa70bc3979 Mon Sep 17 00:00:00
> 2001
> From: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Date: Mon, 17 Dec 2018 20:16:09 +0000
> Subject: [PATCH] Drivers: hv: vmbus: Check for ring when getting debug info
>
> fc96df16a1ce is good and can already fix the "return stack garbage" issue,
> but let's also improve hv_ringbuffer_get_debuginfo(), which would silently
> return stack garbage, if people forget to check channel->state or
> ring_info->ring_buffer, when using the function in the future.
>
> Having an error check in the function would eliminate the potential risk.
>
> Add a Fixes tag to indicate the patch depdendency.
>
> Fixes: fc96df16a1ce ("Drivers: hv: vmbus: Return -EINVAL for the sys files for
> unopened channels")
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
>
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index 64d0c85d5161..1f1a55e07733 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -164,26 +164,25 @@ hv_get_ringbuffer_availbytes(const struct
> hv_ring_buffer_info *rbi,
> }
>
> /* Get various debug metrics for the specified ring buffer. */
> -void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info
> *ring_info,
> - struct hv_ring_buffer_debug_info *debug_info)
> +int hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
> + struct hv_ring_buffer_debug_info *debug_info)
> {
> u32 bytes_avail_towrite;
> u32 bytes_avail_toread;
>
> - if (ring_info->ring_buffer) {
> - hv_get_ringbuffer_availbytes(ring_info,
> - &bytes_avail_toread,
> - &bytes_avail_towrite);
> -
> - debug_info->bytes_avail_toread = bytes_avail_toread;
> - debug_info->bytes_avail_towrite = bytes_avail_towrite;
> - debug_info->current_read_index =
> - ring_info->ring_buffer->read_index;
> - debug_info->current_write_index =
> - ring_info->ring_buffer->write_index;
> - debug_info->current_interrupt_mask =
> - ring_info->ring_buffer->interrupt_mask;
> - }
> + if (!ring_info->ring_buffer)
> + return -EINVAL;
> +
> + hv_get_ringbuffer_availbytes(ring_info,
> + &bytes_avail_toread,
> + &bytes_avail_towrite);
> + debug_info->bytes_avail_toread = bytes_avail_toread;
> + debug_info->bytes_avail_towrite = bytes_avail_towrite;
> + debug_info->current_read_index = ring_info->ring_buffer->read_index;
> + debug_info->current_write_index = ring_info->ring_buffer->write_index;
> + debug_info->current_interrupt_mask
> + = ring_info->ring_buffer->interrupt_mask;
> + return 0;
> }
> EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo);
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index d0ff65675292..403fee01572c 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -313,12 +313,16 @@ static ssize_t out_intr_mask_show(struct device
> *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info outbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> &outbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> + &outbound);
> + if (ret < 0)
> + return ret;
> +
> return sprintf(buf, "%d\n", outbound.current_interrupt_mask);
> }
> static DEVICE_ATTR_RO(out_intr_mask);
> @@ -328,12 +332,15 @@ static ssize_t out_read_index_show(struct device
> *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info outbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> &outbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> + &outbound);
> + if (ret < 0)
> + return ret;
> return sprintf(buf, "%d\n", outbound.current_read_index);
> }
> static DEVICE_ATTR_RO(out_read_index);
> @@ -344,12 +351,15 @@ static ssize_t out_write_index_show(struct device
> *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info outbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> &outbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> + &outbound);
> + if (ret < 0)
> + return ret;
> return sprintf(buf, "%d\n", outbound.current_write_index);
> }
> static DEVICE_ATTR_RO(out_write_index);
> @@ -360,12 +370,15 @@ static ssize_t out_read_bytes_avail_show(struct
> device *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info outbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> &outbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> + &outbound);
> + if (ret < 0)
> + return ret;
> return sprintf(buf, "%d\n", outbound.bytes_avail_toread);
> }
> static DEVICE_ATTR_RO(out_read_bytes_avail);
> @@ -376,12 +389,15 @@ static ssize_t out_write_bytes_avail_show(struct
> device *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info outbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> &outbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound,
> + &outbound);
> + if (ret < 0)
> + return ret;
> return sprintf(buf, "%d\n", outbound.bytes_avail_towrite);
> }
> static DEVICE_ATTR_RO(out_write_bytes_avail);
> @@ -391,12 +407,15 @@ static ssize_t in_intr_mask_show(struct device
> *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info inbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound,
> &inbound);
> + if (ret < 0)
> + return ret;
> +
> return sprintf(buf, "%d\n", inbound.current_interrupt_mask);
> }
> static DEVICE_ATTR_RO(in_intr_mask);
> @@ -406,12 +425,15 @@ static ssize_t in_read_index_show(struct device
> *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info inbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound,
> &inbound);
> + if (ret < 0)
> + return ret;
> +
> return sprintf(buf, "%d\n", inbound.current_read_index);
> }
> static DEVICE_ATTR_RO(in_read_index);
> @@ -421,12 +443,15 @@ static ssize_t in_write_index_show(struct device
> *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info inbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound,
> &inbound);
> + if (ret < 0)
> + return ret;
> +
> return sprintf(buf, "%d\n", inbound.current_write_index);
> }
> static DEVICE_ATTR_RO(in_write_index);
> @@ -437,12 +462,15 @@ static ssize_t in_read_bytes_avail_show(struct
> device *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info inbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound,
> &inbound);
> + if (ret < 0)
> + return ret;
> +
> return sprintf(buf, "%d\n", inbound.bytes_avail_toread);
> }
> static DEVICE_ATTR_RO(in_read_bytes_avail);
> @@ -453,12 +481,15 @@ static ssize_t in_write_bytes_avail_show(struct
> device *dev,
> {
> struct hv_device *hv_dev = device_to_hv_device(dev);
> struct hv_ring_buffer_debug_info inbound;
> + int ret;
>
> if (!hv_dev->channel)
> return -ENODEV;
> - if (hv_dev->channel->state != CHANNEL_OPENED_STATE)
> - return -EINVAL;
> - hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
> +
> + ret = hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound,
> &inbound);
> + if (ret < 0)
> + return ret;
> +
> return sprintf(buf, "%d\n", inbound.bytes_avail_towrite);
> }
> static DEVICE_ATTR_RO(in_write_bytes_avail);
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index f0885cc01db6..dcb6977afce9 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1159,8 +1159,9 @@ struct hv_ring_buffer_debug_info {
> u32 bytes_avail_towrite;
> };
>
> -void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info
> *ring_info,
> - struct hv_ring_buffer_debug_info *debug_info);
> +
> +int hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
> + struct hv_ring_buffer_debug_info *debug_info);
>
> /* Vmbus interface */
> #define vmbus_driver_register(driver) \
We don't need to apply this patch to the 4.4-stable tree, because:
1. This is just a simple code refactoring, which doesn't really have a functional change.
2. We have to backport at least 2 more patches to apply this patch cleanly, which
doesn't deserve the effort to me.
Thanks,
-- Dexuan
