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USB: fix bug in initialization of interface minor numbers

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Recent changes in the usbhid layer exposed a bug in usbcore.  If
CONFIG_USB_DYNAMIC_MINORS is enabled then an interface may be assigned
a minor number of 0.  However interfaces that aren't registered as USB
class devices also have their minor number set to 0, during
initialization.  As a result usb_find_interface() may return the
wrong interface, leading to a crash.

This patch (as1418) fixes the problem by initializing every
interface's minor number to -1.  It also cleans up the
usb_register_dev() function, which besides being somewhat awkwardly
written, does not unwind completely on all its error paths.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Philip J. Turmel <philip@turmel.org>
Tested-by: Gabriel Craciunescu <nix.or.die@googlemail.com>
Tested-by: Alex Riesen <raa.lkml@gmail.com>
Tested-by: Matthias Bayer <jackdachef@gmail.com>
CC: Jiri Kosina <jkosina@suse.cz>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2010-09-21 15:01:53 -04:00 committed by Greg Kroah-Hartman
parent a850ea3037
commit 0026e00523
2 changed files with 17 additions and 19 deletions
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35
drivers/usb/core/file.c
View file

@ -159,9 +159,9 @@ void usb_major_cleanup(void)
int usb_register_dev(struct usb_interface *intf,
struct usb_class_driver *class_driver)
{
int retval = -EINVAL;
int retval;
int minor_base = class_driver->minor_base;
int minor = 0;
int minor;
char name[20];
char *temp;
@ -173,12 +173,17 @@ int usb_register_dev(struct usb_interface *intf,
*/
minor_base = 0;
#endif
intf->minor = -1;
dbg ("looking for a minor, starting at %d", minor_base);
if (class_driver->fops == NULL)
goto exit;
return -EINVAL;
if (intf->minor >= 0)
return -EADDRINUSE;
retval = init_usb_class();
if (retval)
return retval;
dev_dbg(&intf->dev, "looking for a minor, starting at %d", minor_base);
down_write(&minor_rwsem);
for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
@ -186,20 +191,12 @@ int usb_register_dev(struct usb_interface *intf,
continue;
usb_minors[minor] = class_driver->fops;
retval = 0;
intf->minor = minor;
break;
}
up_write(&minor_rwsem);
if (retval)
goto exit;
retval = init_usb_class();
if (retval)
goto exit;
intf->minor = minor;
if (intf->minor < 0)
return -EXFULL;
/* create a usb class device for this usb interface */
snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
@ -213,11 +210,11 @@ int usb_register_dev(struct usb_interface *intf,
"%s", temp);
if (IS_ERR(intf->usb_dev)) {
down_write(&minor_rwsem);
usb_minors[intf->minor] = NULL;
usb_minors[minor] = NULL;
intf->minor = -1;
up_write(&minor_rwsem);
retval = PTR_ERR(intf->usb_dev);
}
exit:
return retval;
}
EXPORT_SYMBOL_GPL(usb_register_dev);

1
drivers/usb/core/message.c
View file

@ -1802,6 +1802,7 @@ free_interfaces:
intf->dev.groups = usb_interface_groups;
intf->dev.dma_mask = dev->dev.dma_mask;
INIT_WORK(&intf->reset_ws, __usb_queue_reset_device);
intf->minor = -1;
device_initialize(&intf->dev);
dev_set_name(&intf->dev, "%d-%s:%d.%d",
dev->bus->busnum, dev->devpath,