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USB: fix concurrent buffer access in the hub driver

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This patch (as849) fixes a bug in the USB hub driver.  A single
pre-allocated buffer is used for all port status reads, but nothing
guarantees exclusive use of the buffer.  A mutex is added to provide
this guarantee.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2007-02-05 09:56:15 -05:00 committed by Greg Kroah-Hartman
parent af59cf404f
commit db90e7a15c
1 changed files with 6 additions and 0 deletions
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6
drivers/usb/core/hub.c
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@ -44,6 +44,7 @@ struct usb_hub {
struct usb_hub_status hub;
struct usb_port_status port;
} *status; /* buffer for status reports */
struct mutex status_mutex; /* for the status buffer */
int error; /* last reported error */
int nerrors; /* track consecutive errors */
@ -535,6 +536,7 @@ static int hub_hub_status(struct usb_hub *hub,
{
int ret;
mutex_lock(&hub->status_mutex);
ret = get_hub_status(hub->hdev, &hub->status->hub);
if (ret < 0)
dev_err (hub->intfdev,
@ -544,6 +546,7 @@ static int hub_hub_status(struct usb_hub *hub,
*change = le16_to_cpu(hub->status->hub.wHubChange);
ret = 0;
}
mutex_unlock(&hub->status_mutex);
return ret;
}
@ -617,6 +620,7 @@ static int hub_configure(struct usb_hub *hub,
ret = -ENOMEM;
goto fail;
}
mutex_init(&hub->status_mutex);
hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
if (!hub->descriptor) {
@ -1396,6 +1400,7 @@ static int hub_port_status(struct usb_hub *hub, int port1,
{
int ret;
mutex_lock(&hub->status_mutex);
ret = get_port_status(hub->hdev, port1, &hub->status->port);
if (ret < 4) {
dev_err (hub->intfdev,
@ -1407,6 +1412,7 @@ static int hub_port_status(struct usb_hub *hub, int port1,
*change = le16_to_cpu(hub->status->port.wPortChange);
ret = 0;
}
mutex_unlock(&hub->status_mutex);
return ret;
}