CVE-2018-14678

An issue was discovered in the Linux kernel through 4.17.11, as used in Xen through 4.11.x. The xen_failsafe_callback entry point in arch/x86/entry/entry_64.S does not properly maintain RBX, which allows local users to cause a denial of service (uninitialized memory usage and system crash). Within Xen, 64-bit x86 PV Linux guest OS users can trigger a guest OS crash or possibly gain privileges.

This kernel update is based on the upstream 4.14.62 and fixes at least the following security issues:

Security researchers from FICORA have identified a remote denial of service attack against the Linux kernel caused by inefficient implementation of TCP segment reassembly, named "SegmentSmack". A remote attacker could consume a lot of CPU resources in the kernel networking stack with just a low bandwidth or single host attack by using lots of small TCP segments packets. Usually large botnets are needed for similar effect. The rate needed for this denial of service attack to be effective is several magnitudes lower than the usual packet processing capability of the machine, as the attack exploits worst case behaviour of existing algorithms (CVE-2018-5390).

An issue was discovered in the Linux kernel through 4.17.11, as used in Xen through 4.11.x. The xen_failsafe_callback entry point in arch/x86/entry/entry_64.S does not properly maintain RBX, which allows local users to cause a denial of service (uninitialized memory usage and system crash). Within Xen, 64-bit x86 PV Linux guest OS users can trigger a guest OS crash or possibly gain privileges (CVE-2018-14678).

Other changes in this update:

• WireGuard has been updated to 0.0.20180802.

For other upstream fixes in this update, see the referenced changelogs.

This kernel-tmb update is based on the upstream 4.14.62 and fixes at least the following security issues:

kernel KVM before versions kernel 4.16, kernel 4.16-rc7, kernel 4.17-rc1, kernel 4.17-rc2 and kernel 4.17-rc3 is vulnerable to a flaw in the way the Linux kernel's KVM hypervisor handled exceptions delivered after a stack switch operation via Mov SS or Pop SS instructions. During the stack switch operation, the processor did not deliver interrupts and exceptions, rather they are delivered once the first instruction after the stack switch is executed. An unprivileged KVM guest user could use this flaw to crash the guest or, potentially, escalate their privileges in the guest (CVE-2018-1087).

Linux kernel vhost since version 4.8 does not properly initialize memory in messages passed between virtual guests and the host operating system in the vhost/vhost.c:vhost_new_msg() function. This can allow local privileged users to read some kernel memory contents when reading from the /dev/vhost-net device file (CVE-2018-1118).

Security researchers from FICORA have identified a remote denial of service attack against the Linux kernel caused by inefficient implementation of TCP segment reassembly, named "SegmentSmack". A remote attacker could consume a lot of CPU resources in the kernel networking stack with just a low bandwidth or single host attack by using lots of small TCP segments packets. Usually large botnets are needed for similar effect. The rate needed for this denial of service attack to be effective is several magnitudes lower than the usual packet processing capability of the machine, as the attack exploits worst case behaviour of existing algorithms (CVE-2018-5390). In the function sbusfb_ioctl_helper() in drivers/video/fbdev/sbuslib.c in the Linux kernel through 4.15, an integer signedness error allows arbitrary information leakage for the FBIOPUTCMAP_SPARC and FBIOGETCMAP_SPARC commands (CVE-2018-6412).

In some circumstances, some operating systems or hypervisors may not expect or properly handle an Intel architecture hardware debug exception. The error appears to be due to developer interpretation of existing documentation for certain Intel architecture interrupt/exception instructions, namely MOV SS and POP SS. An authenticated attacker may be able to read sensitive data in memory or control low-level operating system functions (CVE-2018-8897).

Linux kernel is vulnerable to a heap-based buffer overflow in the fs/ext4/xattr.c:ext4_xattr_set_entry() function. An attacker could exploit this by operating on a mounted crafted ext4 image (CVE-2018-10840).

The kvm functions that were used in the emulation of fxrstor, fxsave, sgdt and sidt were originally meant for task switching, and as such they did not check privilege levels. This allowed guest userspace to guest kernel write (CVE-2018-10853).

A flaw was found in Linux kernel ext4 File System. A use-after-free in ext4_ext_remove_space() when mounting and operating a crafted ext4 image (CVE-2018-10876).

Linux kernel ext4 filesystem is vulnerable to an out-of-bound access in the ext4_ext_drop_refs() function when operating on a crafted ext4 filesystem image (CVE-2018-10877).

A flaw was found in Linux kernel ext4 filesystem. A local user can cause a use-after-free in ext4_xattr_set_entry function and so a denial of service or possibly unspecified other impact by when renaming a file in a crafted ext4 filesystem image (CVE-2018-10879).

A flaw was found in Linux kernel ext4 filesystem code. A stack-out-of-bounds write in ext4_update_inline_data() is possible when mounting and writing to a crafted ext4 image. An attacker could use this to cause a system crash and a denial of service (CVE-2018-10880).

A flaw was found in Linux kernel ext4 filesystem. A local user can cause an out-of-bound access in ext4_get_group_info function and so a denial of service and a system crash by mounting and operating on a crafted ext4 filesystem image (CVE-2018-10881).

A flaw was…

This kernel-linus update is based on the upstream 4.14.62 and fixes at least the following security issues:

kernel KVM before versions kernel 4.16, kernel 4.16-rc7, kernel 4.17-rc1, kernel 4.17-rc2 and kernel 4.17-rc3 is vulnerable to a flaw in the way the Linux kernel's KVM hypervisor handled exceptions delivered after a stack switch operation via Mov SS or Pop SS instructions. During the stack switch operation, the processor did not deliver interrupts and exceptions, rather they are delivered once the first instruction after the stack switch is executed. An unprivileged KVM guest user could use this flaw to crash the guest or, potentially, escalate their privileges in the guest (CVE-2018-1087).

Linux kernel vhost since version 4.8 does not properly initialize memory in messages passed between virtual guests and the host operating system in the vhost/vhost.c:vhost_new_msg() function. This can allow local privileged users to read some kernel memory contents when reading from the /dev/vhost-net device file (CVE-2018-1118).

Security researchers from FICORA have identified a remote denial of service attack against the Linux kernel caused by inefficient implementation of TCP segment reassembly, named "SegmentSmack". A remote attacker could consume a lot of CPU resources in the kernel networking stack with just a low bandwidth or single host attack by using lots of small TCP segments packets. Usually large botnets are needed for similar effect. The rate needed for this denial of service attack to be effective is several magnitudes lower than the usual packet processing capability of the machine, as the attack exploits worst case behaviour of existing algorithms (CVE-2018-5390). In the function sbusfb_ioctl_helper() in drivers/video/fbdev/sbuslib.c in the Linux kernel through 4.15, an integer signedness error allows arbitrary information leakage for the FBIOPUTCMAP_SPARC and FBIOGETCMAP_SPARC commands (CVE-2018-6412).

In some circumstances, some operating systems or hypervisors may not expect or properly handle an Intel architecture hardware debug exception. The error appears to be due to developer interpretation of existing documentation for certain Intel architecture interrupt/exception instructions, namely MOV SS and POP SS. An authenticated attacker may be able to read sensitive data in memory or control low-level operating system functions (CVE-2018-8897).

Linux kernel is vulnerable to a heap-based buffer overflow in the fs/ext4/xattr.c:ext4_xattr_set_entry() function. An attacker could exploit this by operating on a mounted crafted ext4 image (CVE-2018-10840).

The kvm functions that were used in the emulation of fxrstor, fxsave, sgdt and sidt were originally meant for task switching, and as such they did not check privilege levels. This allowed guest userspace to guest kernel write (CVE-2018-10853).

A flaw was found in Linux kernel ext4 File System. A use-after-free in ext4_ext_remove_space() when mounting and operating a crafted ext4 image (CVE-2018-10876).

Linux kernel ext4 filesystem is vulnerable to an out-of-bound access in the ext4_ext_drop_refs() function when operating on a crafted ext4 filesystem image (CVE-2018-10877).

A flaw was found in Linux kernel ext4 filesystem. A local user can cause a use-after-free in ext4_xattr_set_entry function and so a denial of service or possibly unspecified other impact by when renaming a file in a crafted ext4 filesystem image (CVE-2018-10879).

A flaw was found in Linux kernel ext4 filesystem code. A stack-out-of-bounds write in ext4_update_inline_data() is possible when mounting and writing to a crafted ext4 image. An attacker could use this to cause a system crash and a denial of service (CVE-2018-10880).

A flaw was found in Linux kernel ext4 filesystem. A local user can cause an out-of-bound access in ext4_get_group_info function and so a denial of service and a system crash by mounting and operating on a crafted ext4 filesystem image (CVE-2018-10881).

A flaw was…

The SUSE Linux Enterprise 12 SP2 LTSS kernel was updated to receive various security and bugfixes.

• CVE-2018-10853: A flaw was found in the way the KVM hypervisor emulated instructions such as sgdt/sidt/fxsave/fxrstor. It did not check current privilege(CPL) level while emulating unprivileged instructions. An unprivileged guest user/process could use this flaw to potentially escalate privileges inside guest (bnc#1097104).
• CVE-2018-10876: A flaw was found in Linux kernel in the ext4 filesystem code. A use-after-free is possible in ext4_ext_remove_space() function when mounting and operating a crafted ext4 image. (bnc#1099811)
• CVE-2018-10877: Linux kernel ext4 filesystem is vulnerable to an out-of-bound access in the ext4_ext_drop_refs() function when operating on a crafted ext4 filesystem image. (bnc#1099846)
• CVE-2018-10878: A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause an out-of-bounds write and a denial of service or unspecified other impact is possible by mounting and operating a crafted ext4 filesystem image. (bnc#1099813)
• CVE-2018-10879: A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause a use-after-free in ext4_xattr_set_entry function and a denial of service or unspecified other impact may occur by renaming a file in a crafted ext4 filesystem image. (bnc#1099844)
• CVE-2018-10880: Linux kernel is vulnerable to a stack-out-of-bounds write in the ext4 filesystem code when mounting and writing to a crafted ext4 image in ext4_update_inline_data(). An attacker could use this to cause a system crash and a denial of service. (bnc#1099845)
• CVE-2018-10881: A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause an out-of-bound access in ext4_get_group_info function, a denial of service, and a system crash by mounting and operating on a crafted ext4 filesystem image. (bnc#1099864)
• CVE-2018-10882: A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause an out-of-bound write in in fs/jbd2/transaction.c code, a denial of service, and a system crash by unmounting a crafted ext4 filesystem image. (bnc#1099849)
• CVE-2018-10883: A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause an out-of-bounds write in jbd2_journal_dirty_metadata(), a denial of service, and a system crash by mounting and operating on a crafted ext4 filesystem image. (bnc#1099863)
• CVE-2018-10902: It was found that the raw midi kernel driver did not protect against concurrent access which leads to a double realloc (double free) in snd_rawmidi_input_params() and snd_rawmidi_output_status() which are part of snd_rawmidi_ioctl() handler in rawmidi.c file. A malicious local attacker could possibly use this for privilege escalation (bnc#1105322).
• CVE-2018-10938: A crafted network packet sent remotely by an attacker may force the kernel to enter an infinite loop in the cipso_v4_optptr() function in net/ipv4/cipso_ipv4.c leading to a denial-of-service. A certain non-default configuration of LSM (Linux Security Module) and NetLabel should be set up on a system before an attacker could leverage this flaw (bnc#1106016).
• CVE-2018-10940: The cdrom_ioctl_media_changed function in drivers/cdrom/cdrom.c allowed local attackers to use a incorrect bounds check in the CDROM driver CDROM_MEDIA_CHANGED ioctl to read out kernel memory (bnc#1092903).
• CVE-2018-12896: An Integer Overflow in kernel/time/posix-timers.c in the POSIX timer code is caused by the way the overrun accounting works. Depending on interval and expiry time values, the overrun can be larger than INT_MAX, but the accounting is int based. This basically made the accounting values, which are visible to user space via timer_getoverrun(2) and siginfo::si_overrun, random. For example, a local user can cause a denial of service (signed integer overflow) via crafted mmap, futex, timer_create, and timer_settime system calls (bnc#1099922).
• CVE-2018-13093: There is a NULL…

M. Vefa Bicakci and Andy Lutomirski discovered that the kernel did not properly set up all arguments to an error handler callback used when running as a paravirtualized guest. An unprivileged attacker in a paravirtualized guest VM could use this to cause a denial of service (guest VM crash). (CVE-2018-14678)

It was discovered that the KVM implementation in the Linux kernel on ARM 64bit processors did not properly handle some ioctls. An attacker with the privilege to create KVM-based virtual machines could use this to cause a denial of service (host system crash) or execute arbitrary code in the host. (CVE-2018-18021)

Mathias Payer and Hui Peng discovered a use-after-free vulnerability in the Advanced Linux Sound Architecture (ALSA) subsystem. A physically proximate attacker could use this to cause a denial of service (system crash). (CVE-2018-19824)

Shlomi Oberman, Yuli Shapiro, and Ran Menscher discovered an information leak in the Bluetooth implementation of the Linux kernel. An attacker within Bluetooth range could use this to expose sensitive information (kernel memory). (CVE-2019-3459, CVE-2019-3460)

Jann Horn discovered that the KVM implementation in the Linux kernel contained a use-after-free vulnerability. An attacker in a guest VM with access to /dev/kvm could use this to cause a denial of service (guest VM crash). (CVE-2019-6974)

Jim Mattson and Felix Wilhelm discovered a use-after-free vulnerability in the KVM subsystem of the Linux kernel, when using nested virtual machines. A local attacker in a guest VM could use this to cause a denial of service (system crash) or possibly execute arbitrary code in the host system. (CVE-2019-7221)

Felix Wilhelm discovered that an information leak vulnerability existed in the KVM subsystem of the Linux kernel, when nested virtualization is used. A local attacker could use this to expose sensitive information (host system memory to a guest VM). (CVE-2019-7222)

Jann Horn discovered that the eBPF implementation in the Linux kernel was insufficiently hardened against Spectre V1 attacks. A local attacker could use this to expose sensitive information. (CVE-2019-7308)

It was discovered that a use-after-free vulnerability existed in the user- space API for crypto (af_alg) implementation in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2019-8912)

It was discovered that the Linux kernel did not properly deallocate memory when handling certain errors while reading files. A local attacker could use this to cause a denial of service (excessive memory consumption). (CVE-2019-8980)

Jann Horn discovered that the mmap implementation in the Linux kernel did not properly check for the mmap minimum address in some situations. A local attacker could use this to assist exploiting a kernel NULL pointer dereference vulnerability. (CVE-2019-9213)

USN-3931-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu 16.04 LTS and for the Linux Azure kernel for Ubuntu 14.04 LTS.

M. Vefa Bicakci and Andy Lutomirski discovered that the kernel did not properly set up all arguments to an error handler callback used when running as a paravirtualized guest. An unprivileged attacker in a paravirtualized guest VM could use this to cause a denial of service (guest VM crash). (CVE-2018-14678)

It was discovered that the KVM implementation in the Linux kernel on ARM 64bit processors did not properly handle some ioctls. An attacker with the privilege to create KVM-based virtual machines could use this to cause a denial of service (host system crash) or execute arbitrary code in the host. (CVE-2018-18021)

Mathias Payer and Hui Peng discovered a use-after-free vulnerability in the Advanced Linux Sound Architecture (ALSA) subsystem. A physically proximate attacker could use this to cause a denial of service (system crash). (CVE-2018-19824)

Shlomi Oberman, Yuli Shapiro, and Ran Menscher discovered an information leak in the Bluetooth implementation of the Linux kernel. An attacker within Bluetooth range could use this to expose sensitive information (kernel memory). (CVE-2019-3459, CVE-2019-3460)

Jann Horn discovered that the KVM implementation in the Linux kernel contained a use-after-free vulnerability. An attacker in a guest VM with access to /dev/kvm could use this to cause a denial of service (guest VM crash). (CVE-2019-6974)

Jim Mattson and Felix Wilhelm discovered a use-after-free vulnerability in the KVM subsystem of the Linux kernel, when using nested virtual machines. A local attacker in a guest VM could use this to cause a denial of service (system crash) or possibly execute arbitrary code in the host system. (CVE-2019-7221)

Felix Wilhelm discovered that an information leak vulnerability existed in the KVM subsystem of the Linux kernel, when nested virtualization is used. A local attacker could use this to expose sensitive information (host system memory to a guest VM). (CVE-2019-7222)

Jann Horn discovered that the eBPF implementation in the Linux kernel was insufficiently hardened against Spectre V1 attacks. A local attacker could use this to expose sensitive information. (CVE-2019-7308)

It was discovered that a use-after-free vulnerability existed in the user- space API for crypto (af_alg) implementation in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2019-8912)

It was discovered that the Linux kernel did not properly deallocate memory when handling certain errors while reading files. A local attacker could use this to cause a denial of service (excessive memory consumption). (CVE-2019-8980)

Jann Horn discovered that the mmap implementation in the Linux kernel did not properly check for the mmap minimum address in some situations. A local attacker could use this to assist exploiting a kernel NULL pointer dereference vulnerability. (CVE-2019-9213)