Fix lsusb double-free

Am 25.05.2011 00:18 schrieb Greg KH:
> On Wed, May 25, 2011 at 12:02:48AM +0200, Carl-Daniel Hailfinger wrote:
>
>> I was playing with the "authorized" attribute of USB devices in
>> sysfs.
>> If at least one device has authorized=0,
>> "lsusb" will print nothing (not even the host controllers)
>>
> Well, if the device can't be accessed, as you disabled it through the
> authorised=0 setting, lsusb shouldn't really be able to do much with it.
>

Turns out there are two bugs:
libusb screws up walking the bus and claims there are -1 devices (error).
lsusb ignores that and tries to free a nonexisting object.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/lsusb.c b/lsusb.c
index dba88e2..3364493 100644
--- a/lsusb.c
+++ b/lsusb.c
@@ -3848,6 +3848,8 @@ static int list_devices(libusb_context *ctx, int busnum, int devnum, int vendori
 	status = 1; /* 1 device not found, 0 device found */
 
 	num_devs = libusb_get_device_list(ctx, &list);
+	if (num_devs < 0)
+		goto error;
 
 	for (i = 0; i < num_devs; ++i) {
 		libusb_device *dev = list[i];
@@ -3877,6 +3879,7 @@ static int list_devices(libusb_context *ctx, int busnum, int devnum, int vendori
 	}
 
 	libusb_free_device_list(list, 0);
+error:
 	return status;
 }