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Alan Stern 0173a68bfb USB: dummy-hcd: fix infinite-loop resubmission bug
The dummy-hcd HCD/UDC emulator tries not to do too much work during
each timer interrupt.  But it doesn't try very hard; currently all
it does is limit the total amount of bulk data transferred.  Other
transfer types aren't limited, and URBs that transfer no data (because
of an error, perhaps) don't count toward the limit, even though on a
real USB bus they would consume at least a minimum overhead.

This means it's possible to get the driver stuck in an infinite loop,
for example, if the host class driver resubmits an URB every time it
completes (which is common for interrupt URBs).  Each time the URB is
resubmitted it gets added to the end of the pending-URBs list, and
dummy-hcd doesn't stop until that list is empty.  Andrey Konovalov was
able to trigger this failure mode using the syzkaller fuzzer.

This patch fixes the infinite-loop problem by restricting the URBs
handled during each timer interrupt to those that were already on the
pending list when the interrupt routine started.  Newly added URBs
won't be processed until the next timer interrupt.  The problem of
properly accounting for non-bulk bandwidth (as well as packet and
transaction overhead) is not addressed here.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
2017-09-28 12:30:56 +03:00
arch Merge branch 'for-linus-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2017-09-16 12:03:25 -07:00
block
certs
crypto
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-16 11:28:59 -07:00
drivers USB: dummy-hcd: fix infinite-loop resubmission bug 2017-09-28 12:30:56 +03:00
firmware firmware: Restore support for built-in firmware 2017-09-16 10:58:48 -07:00
fs Some cleanups and a big bug fix for ACLs. When I was reviewing Jan Kara's 2017-09-15 12:16:18 -07:00
include USB: fix out-of-bounds in usb_set_configuration 2017-09-19 17:27:16 +02:00
init
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-16 11:28:59 -07:00
lib
mm
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-16 11:28:59 -07:00
samples
scripts Firmware removal patch for 4.14-rc1 2017-09-15 12:58:55 -07:00
security
sound vfs: constify path argument to kernel_read_file_from_path 2017-09-14 20:18:45 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-16 11:28:59 -07:00
usr
virt kvm: Serialize wq active checks in kvm_vcpu_wake_up() 2017-09-15 16:57:12 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-16 11:28:59 -07:00
Makefile Linux 4.14-rc1 2017-09-16 15:47:51 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.