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When the isochronous transfer support was introduced, and the xHCI driver switched to using urb->hcpriv to store an "urb_priv" pointer, a couple of memory leaks were introduced into the URB enqueue function in its error handling paths. xhci_urb_enqueue allocates urb_priv, but it doesn't free it if changing the control endpoint's max packet size fails or the bulk endpoint is in the middle of allocating or deallocating streams. xhci_urb_enqueue also doesn't free urb_priv if any of the four endpoint types' enqueue functions fail. Instead, it expects those functions to free urb_priv if an error occurs. However, the bulk, control, and interrupt enqueue functions do not free urb_priv if the endpoint ring is NULL. It will, however, get freed if prepare_transfer() fails in those enqueue functions. Several of the error paths in the isochronous endpoint enqueue function also fail to free it. xhci_queue_isoc_tx_prepare() doesn't free urb_priv if prepare_ring() indicates there is not enough room for all the isochronous TDs in this URB. If individual isochronous TDs fail to be queued (perhaps due to an endpoint state change), urb_priv is also leaked. This argues that the freeing of urb_priv should be done in the function that allocated it, xhci_urb_enqueue. This patch looks rather ugly, but refactoring the code will have to wait because this patch needs to be backported to stable kernels. This patch should be backported to kernels as old as 2.6.36. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: Andiry Xu <andiry.xu@amd.com> Cc: stable@kernel.org
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("khubd").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.