[SECURITY] [DLA 1885-1] linux-4.9 security update

Package : linux-4.9
Version : 4.9.168-1+deb9u5~deb8u1
CVE ID : CVE-2017-18509 CVE-2018-5995 CVE-2018-20836 CVE-2018-20856
CVE-2019-1125 CVE-2019-3882 CVE-2019-3900 CVE-2019-10207
CVE-2019-10638 CVE-2019-10639 CVE-2019-13631 CVE-2019-13648
CVE-2019-14283 CVE-2019-14284

Several vulnerabilities have been discovered in the Linux kernel that
may lead to a privilege escalation, denial of service or information
leaks.

CVE-2017-18509

Denis Andzakovic reported a missing type check in the IPv4 multicast
routing implementation. A user with the CAP_NET_ADMIN capability (in
any user namespace) could use this for denial-of-service (memory
corruption or crash) or possibly for privilege escalation.

CVE-2018-5995

ADLab of VenusTech discovered that the kernel logged the virtual
addresses assigned to per-CPU data, which could make it easier to
exploit other vulnerabilities.

CVE-2018-20836

chenxiang reported a race condition in libsas, the kernel
subsystem supporting Serial Attached SCSI (SAS) devices, which
could lead to a use-after-free.  It is not clear how this might be
exploited.

CVE-2018-20856

Xiao Jin reported a potential double-free in the block subsystem,
in case an error occurs while initialising the I/O scheduler for a
block device.  It is not clear how this might be exploited.

CVE-2019-1125

It was discovered that most x86 processors could speculatively
skip a conditional SWAPGS instruction used when entering the
kernel from user mode, and/or could speculatively execute it when
it should be skipped.  This is a subtype of Spectre variant 1,
which could allow local users to obtain sensitive information from
the kernel or other processes.  It has been mitigated by using
memory barriers to limit speculative execution.  Systems using an
i386 kernel are not affected as the kernel does not use SWAPGS.

CVE-2019-3882

It was found that the vfio implementation did not limit the number
of DMA mappings to device memory.  A local user granted ownership
of a vfio device could use this to cause a denial of service
(out-of-memory condition).

CVE-2019-3900

It was discovered that vhost drivers did not properly control the
amount of work done to service requests from guest VMs.  A
malicious guest could use this to cause a denial-of-service
(unbounded CPU usage) on the host.

CVE-2019-10207

The syzkaller tool found a potential null dereference in various
drivers for UART-attached Bluetooth adapters.  A local user with
access to a pty device or other suitable tty device could use this
for denial-of-service (BUG/oops).

CVE-2019-10638

Amit Klein and Benny Pinkas discovered that the generation of IP
packet IDs used a weak hash function, "jhash".  This could enable
tracking individual computers as they communicate with different
remote servers and from different networks.  The "siphash"
function is now used instead.

CVE-2019-10639

Amit Klein and Benny Pinkas discovered that the generation of IP
packet IDs used a weak hash function that incorporated a kernel
virtual address.  This hash function is no longer used for IP IDs,
although it is still used for other purposes in the network stack.

CVE-2019-13631

It was discovered that the gtco driver for USB input tablets could
overrun a stack buffer with constant data while parsing the device's
descriptor.  A physically present user with a specially
constructed USB device could use this to cause a denial-of-service
(BUG/oops), or possibly for privilege escalation.

CVE-2019-13648

Praveen Pandey reported that on PowerPC (ppc64el) systems without
Transactional Memory (TM), the kernel would still attempt to
restore TM state passed to the sigreturn() system call.  A local
user could use this for denial-of-service (oops).

CVE-2019-14283

The syzkaller tool found a missing bounds check in the floppy disk
driver.  A local user with access to a floppy disk device, with a
disk present, could use this to read kernel memory beyond the
I/O buffer, possibly obtaining sensitive information.

CVE-2019-14284

The syzkaller tool found a potential division-by-zero in the
floppy disk driver.  A local user with access to a floppy disk
device could use this for denial-of-service (oops).

(CVE ID not yet assigned)

Denis Andzakovic reported a possible use-after-free in the
TCP sockets implementation.  A local user could use this for
denial-of-service (memory corruption or crash) or possibly
for privilege escalation.

(CVE ID not yet assigned)

The netfilter conntrack subsystem used kernel addresses as
user-visible IDs, which could make it easier to exploit other
security vulnerabilities.

XSA-300

Julien Grall reported that Linux does not limit the amount of memory
which a domain will attempt to baloon out, nor limits the amount of
"foreign / grant map" memory which any individual guest can consume,
leading to denial of service conditions (for host or guests).

For Debian 8 "Jessie", these problems have been fixed in version
4.9.168-1+deb9u5~deb8u1.

We recommend that you upgrade your linux-4.9 packages.

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS

Ben Hutchings - Debian developer, member of kernel, installer and LTS teams
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