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Alan Stern 54f83b8c8e USB: gadget: Reject endpoints with 0 maxpacket value
Endpoints with a maxpacket length of 0 are probably useless.  They
can't transfer any data, and it's not at all unlikely that a UDC will
crash or hang when trying to handle a non-zero-length usb_request for
such an endpoint.  Indeed, dummy-hcd gets a divide error when trying
to calculate the remainder of a transfer length by the maxpacket
value, as discovered by the syzbot fuzzer.

Currently the gadget core does not check for endpoints having a
maxpacket value of 0.  This patch adds a check to usb_ep_enable(),
preventing such endpoints from being used.

As far as I know, none of the gadget drivers in the kernel tries to
create an endpoint with maxpacket = 0, but until now there has been
nothing to prevent userspace programs under gadgetfs or configfs from
doing it.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: syzbot+8ab8bf161038a8768553@syzkaller.appspotmail.com
CC: <stable@vger.kernel.org>
Acked-by: Felipe Balbi <balbi@kernel.org>

Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1910281052370.1485-100000@iolanthe.rowland.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-29 09:56:18 +01:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-10-27 07:14:40 -04:00
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drivers USB: gadget: Reject endpoints with 0 maxpacket value 2019-10-29 09:56:18 +01:00
fs Seven cifs/smb3 fixes, including three for stable 2019-10-27 06:41:52 -04:00
include Driver core fix for 5.4-rc5 2019-10-26 15:23:08 -04:00
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kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-10-27 07:04:22 -04:00
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tools usbip: tools: Fix read_usb_vudc_device() error path handling 2019-10-28 17:51:06 +01:00
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.mailmap A few MIPS fixes: 2019-10-26 19:43:12 -04:00
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MAINTAINERS A few MIPS fixes: 2019-10-26 19:43:12 -04:00
Makefile Linux 5.4-rc5 2019-10-27 13:19:19 -04:00
README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.