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staging: usbip: cleanup and fix of vhci_hub_status 

Changed setting the status bits to a byte-oriented approach. Number of
written status bits is now based on VHCI_NPORT, instead of casting
status buffer to a long. This fixes a stack corruption bug on 64-bit
based architectures, and potential byte order / endianness related
issues.

In addition updated function comments, and log statements.

Signed-off-by: Bart Westgeest <bart@elbrys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bart Westgeest 2012-06-13 15:37:18 -04:00 committed by Greg Kroah-Hartman
parent b4b700c5a6
commit 7489301a15
1 changed files with 11 additions and 28 deletions
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39
drivers/staging/usbip/vhci_hcd.c
View File

@ -178,44 +178,32 @@ void rh_port_disconnect(int rhport)
| USB_PORT_STAT_C_RESET) << 16)
/*
* This function is almostly the same as dummy_hcd.c:dummy_hub_status() without
* suspend/resume support. But, it is modified to provide multiple ports.
* Returns 0 if the status hasn't changed, or the number of bytes in buf.
* Ports are 0-indexed from the HCD point of view,
* and 1-indexed from the USB core pointer of view.
*
* @buf: a bitmap to show which port status has been changed.
* bit 0: reserved or used for another purpose?
* bit 0: reserved
* bit 1: the status of port 0 has been changed.
* bit 2: the status of port 1 has been changed.
* ...
* bit 7: the status of port 6 has been changed.
* bit 8: the status of port 7 has been changed.
* ...
* bit 15: the status of port 14 has been changed.
*
* So, the maximum number of ports is 31 ( port 0 to port 30) ?
*
* The return value is the actual transferred length in byte. If nothing has
* been changed, return 0. In the case that the number of ports is less than or
* equal to 6 (VHCI_NPORTS==7), return 1.
*
*/
static int vhci_hub_status(struct usb_hcd *hcd, char *buf)
{
struct vhci_hcd *vhci;
unsigned long flags;
int retval = 0;
/* the enough buffer is allocated according to USB_MAXCHILDREN */
unsigned long *event_bits = (unsigned long *) buf;
int retval;
int rhport;
int changed = 0;
*event_bits = 0;
retval = DIV_ROUND_UP(VHCI_NPORTS + 1, 8);
memset(buf, 0, retval);
vhci = hcd_to_vhci(hcd);
spin_lock_irqsave(&vhci->lock, flags);
if (!HCD_HW_ACCESSIBLE(hcd)) {
usbip_dbg_vhci_rh("hw accessible flag in on?\n");
usbip_dbg_vhci_rh("hw accessible flag not on?\n");
goto done;
}
@ -223,9 +211,9 @@ static int vhci_hub_status(struct usb_hcd *hcd, char *buf)
for (rhport = 0; rhport < VHCI_NPORTS; rhport++) {
if ((vhci->port_status[rhport] & PORT_C_MASK)) {
/* The status of a port has been changed, */
usbip_dbg_vhci_rh("port %d is changed\n", rhport);
usbip_dbg_vhci_rh("port %d status changed\n", rhport);
*event_bits |= 1 << (rhport + 1);
buf[(rhport + 1) / 8] |= 1 << (rhport + 1) % 8;
changed = 1;
}
}
@ -235,14 +223,9 @@ static int vhci_hub_status(struct usb_hcd *hcd, char *buf)
if (hcd->state == HC_STATE_SUSPENDED)
usb_hcd_resume_root_hub(hcd);
if (changed)
retval = 1 + (VHCI_NPORTS / 8);
else
retval = 0;
done:
spin_unlock_irqrestore(&vhci->lock, flags);
return retval;
return changed ? retval : 0;
}
/* See hub_configure in hub.c */