Messages in this thread Patch in this message | | | Date | Fri, 13 Mar 2009 17:05:30 -0700 | From | Greg KH <> | Subject | [patch 22/96] USB: usb_get_string should check the descriptor type |
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2.6.27-stable review patch. If anyone has any objections, please let us know.
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From: Alan Stern <stern@rowland.harvard.edu>
commit 67f5a4ba9741fcef3f4db3509ad03565d9e33af2 upstream.
This patch (as1218) fixes a problem with a radio-control joystick used in the "walkera 4#3" helicopter. This device responds to the initial Get-String-Descriptor request for string 0 (which is really the list of supported languages) by sending its config descriptor! The usb_get_string() routine needs to check whether it got the right type of descriptor.
Oddly enough, this sort of check is already present in usb_get_descriptor(). The patch changes the error code from -EPROTO to -ENODATA, because -EPROTO shows up in so many other contexts to indicate a hardware failure rather than a firmware error.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Guillermo Jarabo <williamjap@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/usb/core/message.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -651,7 +651,7 @@ int usb_get_descriptor(struct usb_device if (result <= 0 && result != -ETIMEDOUT) continue; if (result > 1 && ((u8 *)buf)[1] != type) { - result = -EPROTO; + result = -ENODATA; continue; } break; @@ -694,8 +694,13 @@ static int usb_get_string(struct usb_dev USB_REQ_GET_DESCRIPTOR, USB_DIR_IN, (USB_DT_STRING << 8) + index, langid, buf, size, USB_CTRL_GET_TIMEOUT); - if (!(result == 0 || result == -EPIPE)) - break; + if (result == 0 || result == -EPIPE) + continue; + if (result > 1 && ((u8 *) buf)[1] != USB_DT_STRING) { + result = -ENODATA; + continue; + } + break; } return result; }
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