Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
firewire: Preserve response data alignment bug when it is harmless
diff --git a/drivers/firewire/fw-cdev.c b/drivers/firewire/fw-cdev.c
index bc81d6f..2e6d584 100644
--- a/drivers/firewire/fw-cdev.c
+++ b/drivers/firewire/fw-cdev.c
@@ -369,22 +369,33 @@
struct response *response = data;
struct client *client = response->client;
unsigned long flags;
+ struct fw_cdev_event_response *r = &response->response;
- if (length < response->response.length)
- response->response.length = length;
+ if (length < r->length)
+ r->length = length;
if (rcode == RCODE_COMPLETE)
- memcpy(response->response.data, payload,
- response->response.length);
+ memcpy(r->data, payload, r->length);
spin_lock_irqsave(&client->lock, flags);
list_del(&response->resource.link);
spin_unlock_irqrestore(&client->lock, flags);
- response->response.type = FW_CDEV_EVENT_RESPONSE;
- response->response.rcode = rcode;
- queue_event(client, &response->event, &response->response,
- sizeof(response->response) + response->response.length,
- NULL, 0);
+ r->type = FW_CDEV_EVENT_RESPONSE;
+ r->rcode = rcode;
+
+ /*
+ * In the case that sizeof(*r) doesn't align with the position of the
+ * data, and the read is short, preserve an extra copy of the data
+ * to stay compatible with a pre-2.6.27 bug. Since the bug is harmless
+ * for short reads and some apps depended on it, this is both safe
+ * and prudent for compatibility.
+ */
+ if (r->length <= sizeof(*r) - offsetof(typeof(*r), data))
+ queue_event(client, &response->event, r, sizeof(*r),
+ r->data, r->length);
+ else
+ queue_event(client, &response->event, r, sizeof(*r) + r->length,
+ NULL, 0);
}
static int ioctl_send_request(struct client *client, void *buffer)