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    Subject[patch 013/101] USB: fix concurrent buffer access in the hub driver

    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>

    ---
    drivers/usb/core/hub.c | 6 ++++++
    1 file changed, 6 insertions(+)

    --- linux-2.6.20.1.orig/drivers/usb/core/hub.c
    +++ linux-2.6.20.1/drivers/usb/core/hub.c
    @@ -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 */
    @@ -538,6 +539,7 @@ static int hub_hub_status(struct usb_hub
    {
    int ret;

    + mutex_lock(&hub->status_mutex);
    ret = get_hub_status(hub->hdev, &hub->status->hub);
    if (ret < 0)
    dev_err (hub->intfdev,
    @@ -547,6 +549,7 @@ static int hub_hub_status(struct usb_hub
    *change = le16_to_cpu(hub->status->hub.wHubChange);
    ret = 0;
    }
    + mutex_unlock(&hub->status_mutex);
    return ret;
    }

    @@ -620,6 +623,7 @@ static int hub_configure(struct usb_hub
    ret = -ENOMEM;
    goto fail;
    }
    + mutex_init(&hub->status_mutex);

    hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
    if (!hub->descriptor) {
    @@ -1418,6 +1422,7 @@ static int hub_port_status(struct usb_hu
    {
    int ret;

    + mutex_lock(&hub->status_mutex);
    ret = get_port_status(hub->hdev, port1, &hub->status->port);
    if (ret < 4) {
    dev_err (hub->intfdev,
    @@ -1429,6 +1434,7 @@ static int hub_port_status(struct usb_hu
    *change = le16_to_cpu(hub->status->port.wPortChange);
    ret = 0;
    }
    + mutex_unlock(&hub->status_mutex);
    return ret;
    }

    --
    -
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