[34-longterm 165/260] USB: fix bug in initialization of interface minor numbers

Paul Gortmaker
2011-01-02T07:44:09Z

From: Alan Stern <stern@rowland.harvard.edu>

commit 0026e00523a85b90a92a93ddf6660939ecef3e54 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/usb/core/file.c | 35 ++++++++++++++++-------------------
drivers/usb/core/message.c | 1 +
2 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/core/file.c b/drivers/usb/core/file.c
index f06f5db..1e6ccef 100644
--- a/drivers/usb/core/file.c
+++ b/drivers/usb/core/file.c
@@ -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);
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 794dca2..ad1f359 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1817,6 +1817,7 @@ 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,
--
1.7.3.3