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@vger.kernel.org
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 61 insertions, 30 deletions

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);