Drivers: hv: vmbus: Check for ring when getting debug info

commit ba50bf1ce9a51fc97db58b96d01306aa70bc3979 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 3f8dde8..74c1dfb 100644 (file)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -141,26 +141,25 @@ static u32 hv_copyto_ringbuffer(
 }
 
 /* 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 4218a61..1fd812e 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -297,12 +297,16 @@ 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);
@@ -312,12 +316,15 @@ 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);
@@ -328,12 +335,15 @@ 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);
@@ -344,12 +354,15 @@ 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);
@@ -360,12 +373,15 @@ 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);
@@ -375,12 +391,15 @@ 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);
@@ -390,12 +409,15 @@ 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);
@@ -405,12 +427,15 @@ 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);
@@ -421,12 +446,15 @@ 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);
@@ -437,12 +465,15 @@ 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 d1324d3..8d3ca6d 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1130,8 +1130,9 @@ 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)  \