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Wenwen Wang ebe79f9cf4 isdn: eicon: fix a missing-check bug 
[ Upstream commit 6009d1fe6b ]

In divasmain.c, the function divas_write() firstly invokes the function
diva_xdi_open_adapter() to open the adapter that matches with the adapter
number provided by the user, and then invokes the function diva_xdi_write()
to perform the write operation using the matched adapter. The two functions
diva_xdi_open_adapter() and diva_xdi_write() are located in diva.c.

In diva_xdi_open_adapter(), the user command is copied to the object 'msg'
from the userspace pointer 'src' through the function pointer 'cp_fn',
which eventually calls copy_from_user() to do the copy. Then, the adapter
number 'msg.adapter' is used to find out a matched adapter from the
'adapter_queue'. A matched adapter will be returned if it is found.
Otherwise, NULL is returned to indicate the failure of the verification on
the adapter number.

As mentioned above, if a matched adapter is returned, the function
diva_xdi_write() is invoked to perform the write operation. In this
function, the user command is copied once again from the userspace pointer
'src', which is the same as the 'src' pointer in diva_xdi_open_adapter() as
both of them are from the 'buf' pointer in divas_write(). Similarly, the
copy is achieved through the function pointer 'cp_fn', which finally calls
copy_from_user(). After the successful copy, the corresponding command
processing handler of the matched adapter is invoked to perform the write
operation.

It is obvious that there are two copies here from userspace, one is in
diva_xdi_open_adapter(), and one is in diva_xdi_write(). Plus, both of
these two copies share the same source userspace pointer, i.e., the 'buf'
pointer in divas_write(). Given that a malicious userspace process can race
to change the content pointed by the 'buf' pointer, this can pose potential
security issues. For example, in the first copy, the user provides a valid
adapter number to pass the verification process and a valid adapter can be
found. Then the user can modify the adapter number to an invalid number.
This way, the user can bypass the verification process of the adapter
number and inject inconsistent data.

This patch reuses the data copied in
diva_xdi_open_adapter() and passes it to diva_xdi_write(). This way, the
above issues can be avoided.

Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2018-06-11 22:49:19 +02:00
Documentation pinctrl: artpec6: dt: add missing pin group uart5nocts 2018-05-30 07:52:37 +02:00
arch powerpc/mm/slice: Fix hugepage allocation at hint address on 8xx 2018-06-05 11:42:00 +02:00
block block: display the correct diskname for bio 2018-05-30 07:52:09 +02:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto PKCS#7: fix direct verification of SignerInfo signature 2018-05-30 07:52:01 +02:00
drivers isdn: eicon: fix a missing-check bug 2018-06-11 22:49:19 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs btrfs: define SUPER_FLAG_METADUMP_V2 2018-06-11 22:49:18 +02:00
include ipv6: omit traffic class when calculating flow hash 2018-06-11 22:49:19 +02:00
init kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2018-02-22 15:42:23 +01:00
ipc ipc/shm: fix shmat() nil address after round-down when remapping 2018-05-30 07:51:49 +02:00
kernel tracing: Make the snapshot trigger work with instances 2018-06-05 11:41:56 +02:00
lib lib/test_kmod.c: fix limit check on number of test devices created 2018-05-30 07:52:14 +02:00
mm mmap: relax file size limit for regular files 2018-06-11 22:49:18 +02:00
net ipv6: omit traffic class when calculating flow hash 2018-06-11 22:49:19 +02:00
samples samples/bpf: Partially fixes the bpf.o build 2018-04-26 11:02:12 +02:00
scripts kconfig: Avoid format overflow warning from GCC 8.1 2018-06-11 22:49:18 +02:00
security selinux: KASAN: slab-out-of-bounds in xattr_getsecurity 2018-06-05 11:41:56 +02:00
sound ASoC: Intel: sst: remove redundant variable dma_dev_name 2018-06-05 11:41:57 +02:00
tools objtool: Fix "noreturn" detection for recursive sibling calls 2018-06-05 11:41:55 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: vgic: Add missing irq_lock to vgic_mmio_read_pending 2018-05-30 07:52:15 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
…
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.48 2018-06-05 11:42:00 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.