Security update for the Linux Kernel

SUSE Security Update: Security update for the Linux Kernel
Announcement ID: SUSE-SU-2021:3929-1
Rating: important
References: #1068032 #1087082 #1098425 #1100416 #1119934 #1129735 #1171217 #1171420 #1173346 #1176724 #1183089 #1184673 #1186109 #1186390 #1188172 #1188325 #1188563 #1188601 #1188838 #1188876 #1188983 #1188985 #1189057 #1189262 #1189291 #1189399 #1189706 #1190023 #1190025 #1190067 #1190117 #1190159 #1190276 #1190349 #1190351 #1190601 #1191193 #1191315 #1191790 #1191958 #1191961 #1192781 #802154
Cross-References:CVE-2017-5753 CVE-2018-13405 CVE-2018-16882 CVE-2020-0429 CVE-2020-12655 CVE-2020-14305 CVE-2020-3702 CVE-2021-20265 CVE-2021-20322 CVE-2021-31916 CVE-2021-33033 CVE-2021-34556 CVE-2021-34981 CVE-2021-3542 CVE-2021-35477 CVE-2021-3640 CVE-2021-3653 CVE-2021-3655 CVE-2021-3659 CVE-2021-3679 CVE-2021-3715 CVE-2021-37159 CVE-2021-3732 CVE-2021-3752 CVE-2021-3753 CVE-2021-37576 CVE-2021-3760 CVE-2021-3772 CVE-2021-38160 CVE-2021-38198 CVE-2021-38204 CVE-2021-3896 CVE-2021-40490 CVE-2021-42008 CVE-2021-42739 CVE-2021-43389
Affected Products:
  • SUSE Linux Enterprise Server 12-SP2-BCL

An update that solves 36 vulnerabilities and has 7 fixes is now available.


The SUSE Linux Enterprise 12 SP2 LTSS kernel was updated to receive various security and bugfixes.
The following security bugs were fixed:

  • Unprivileged BPF has been disabled by default to reduce attack surface as too many security issues have happened in the past (jsc#SLE-22573)

You can reenable via systemctl setting /proc/sys/kernel/unprivileged_bpf_disabled to 0. (kernel.unprivileged_bpf_disabled = 0)
  • CVE-2017-5753: Systems with microprocessors utilizing speculative execution and branch prediction may have allowed unauthorized disclosure of information to an attacker with local user access via a side-channel analysis (bnc#1068032). Additional spectrev1 fixes were added to the eBPF code.
  • CVE-2018-13405: The inode_init_owner function in fs/inode.c allowed local users to create files with an unintended group ownership, in a scenario where a directory is SGID to a certain group and is writable by a user who is not a member of that group. Here, the non-member can trigger creation of a plain file whose group ownership is that group. The intended behavior was that the non-member can trigger creation of a directory (but not a plain file) whose group ownership is that group. The non-member can escalate privileges by making the plain file executable and SGID (bnc#1087082 bnc#1100416 bnc#1129735).
  • CVE-2018-16882: A use-after-free issue was found in the way the KVM hypervisor processed posted interrupts when nested(=1) virtualization is enabled. In nested_get_vmcs12_pages(), in case of an error while processing posted interrupt address, it unmaps the 'pi_desc_page' without resetting 'pi_desc' descriptor address, which is later used in pi_test_and_clear_on(). A guest user/process could use this flaw to crash the host kernel resulting in DoS or potentially gain privileged access to a system. Kernel versions and are vulnerable (bnc#1119934).
  • CVE-2020-0429: In l2tp_session_delete and related functions of l2tp_core.c, there is possible memory corruption due to a use after free. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation (bnc#1176724).
  • CVE-2020-12655: An issue was discovered in xfs_agf_verify in fs/xfs/libxfs/xfs_alloc.c in the Linux kernel Attackers may trigger a sync of excessive duration via an XFS v5 image with crafted metadata, aka CID-d0c7feaf8767 (bnc#1171217).
  • CVE-2020-14305: An out-of-bounds memory write flaw was found in how the Linux kernel’s Voice Over IP H.323 connection tracking functionality handled connections on ipv6 port 1720. This flaw allowed an unauthenticated remote user to crash the system, causing a denial of service. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability (bnc#1173346).
  • CVE-2020-3702: Specifically timed and handcrafted traffic can cause internal errors in a WLAN device that lead to improper layer 2 Wi-Fi encryption with a consequent possibility of information disclosure over the air for a discrete set of traffic (bnc#1191193).
  • CVE-2021-20265: A flaw was found in the way memory resources were freed in the unix_stream_recvmsg function in the Linux kernel when a signal was pending. This flaw allowed an unprivileged local user to crash the system by exhausting available memory. The highest threat from this vulnerability is to system availability (bnc#1183089).
  • CVE-2021-31916: An out-of-bounds (OOB) memory write flaw was found in list_devices in drivers/md/dm-ioctl.c in the Multi-device driver module in the Linux kernel A bound check failure allowed an attacker with special user (CAP_SYS_ADMIN) privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability (bnc#1192781).
  • CVE-2021-33033: The Linux kernel has a use-after-free in cipso_v4_genopt in net/ipv4/cipso_ipv4.c because the CIPSO and CALIPSO refcounting for the DOI definitions is mishandled, aka CID-ad5d07f4a9cd. This leads to writing an arbitrary value (bnc#1186109 bnc#1186390 bnc#1188876).
  • CVE-2021-34556: In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects the possibility of uninitialized memory locations on the BPF stack (bnc#1188983).
  • CVE-2021-34981: Fixed file refcounting in cmtp when cmtp_attach_device fails (bsc#1191961).
  • CVE-2021-3542: Fixed heap buffer overflow in firedtv driver (bsc#1186063).
  • CVE-2021-35477: In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because a certain preempting store operation did not necessarily occur before a store operation that has an attacker-controlled value (bnc#1188985).
  • CVE-2021-3640: Fixed a Use-After-Free vulnerability in function sco_sock_sendmsg() in the bluetooth stack (bsc#1188172).
  • CVE-2021-3653: A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "int_ctl" field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape. (bnc#1189399).
  • CVE-2021-3655: A vulnerability was found in the Linux kernel in versions prior to v5.14-rc1. Missing size validations on inbound SCTP packets may have allowed the kernel to read uninitialized memory (bnc#1188563).
  • CVE-2021-3659: Fixed a NULL pointer dereference in llsec_key_alloc() in net/mac802154/llsec.c (bsc#1188876).
  • CVE-2021-3679: A lack of CPU resource in the tracing module functionality was found in the way user uses trace ring buffer in a specific way. Only privileged local users (with CAP_SYS_ADMIN capability) could use this flaw to starve the resources causing denial of service (bnc#1189057).
  • CVE-2021-37159: hso_free_net_device in drivers/net/usb/hso.c in the Linux kernel calls unregister_netdev without checking for the NETREG_REGISTERED state, leading to a use-after-free and a double free (bnc#1188601).
  • CVE-2021-3715: Fixed a use-after-free in route4_change() in net/sched/cls_route.c (bsc#1190349).
  • CVE-2021-3732: Mounting overlayfs inside an unprivileged user namespace can reveal files (bsc#1189706).
  • CVE-2021-3752: Fixed a use after free vulnerability in the Linux kernel's bluetooth module. (bsc#1190023)
  • CVE-2021-3753: Fixed race out-of-bounds in virtual terminal handling (bsc#1190025).
  • CVE-2021-37576: arch/powerpc/kvm/book3s_rtas.c on the powerpc platform allowed KVM guest OS users to cause host OS memory corruption via rtas_args.nargs, aka CID-f62f3c20647e (bnc#1188838 bnc#1190276).
  • CVE-2021-3760: Fixed a use-after-free vulnerability with the ndev->rf_conn_info object (bsc#1190067).
  • CVE-2021-3772: Fixed sctp vtag check in sctp_sf_ootb (bsc#1190351).
  • CVE-2021-38160: Data corruption or loss could be triggered by an untrusted device that supplies a buf->len value exceeding the buffer size in drivers/char/virtio_console.c (bsc#1190117)
  • CVE-2021-38198: arch/x86/kvm/mmu/paging_tmpl.h incorrectly computed the access permissions of a shadow page, leading to a missing guest protection page fault (bnc#1189262).
  • CVE-2021-38204: drivers/usb/host/max3421-hcd.c allowed physically proximate attackers to cause a denial of service (use-after-free and panic) by removing a MAX-3421 USB device in certain situations (bnc#1189291).
  • CVE-2021-3896: Fixed a array-index-out-bounds in detach_capi_ctr in drivers/isdn/capi/kcapi.c (bsc#1191958).
  • CVE-2021-40490: A race condition was discovered in ext4_write_inline_data_end in fs/ext4/inline.c in the ext4 subsystem in the Linux kernel (bnc#1190159)
  • CVE-2021-42008: The decode_data function in drivers/net/hamradio/6pack.c in the Linux kernel has a slab out-of-bounds write. Input from a process that has the CAP_NET_ADMIN capability can lead to root access (bnc#1191315).
  • CVE-2021-42739: The firewire subsystem in the Linux kernel has a buffer overflow related to drivers/media/firewire/firedtv-avc.c and drivers/media/firewire/firedtv-ci.c, because avc_ca_pmt mishandled bounds checking (bnc#1184673).
  • CVE-2021-43389: An issue was discovered in the Linux kernel There was an array-index-out-of-bounds flaw in the detach_capi_ctr function in drivers/isdn/capi/kcapi.c (bnc#1191958).
  • - ipv4: make exception cache less predictible (bsc#1191790, CVE-2021-20322).

The following non-security bugs were fixed:
  • Update config files: Add CONFIG_BPF_UNPRIV_DEFAULT_OFF is not set
  • bpf: Add kconfig knob for disabling unpriv bpf by default (jsc#SLE-22918)
  • bpf: Disallow unprivileged bpf by default (jsc#SLE-22918).
  • bpf: properly enforce index mask to prevent out-of-bounds speculation (bsc#1098425).
  • btrfs: reloc: clear DEAD_RELOC_TREE bit for orphan roots to prevent runaway balance (bsc#1188325).
  • btrfs: reloc: fix reloc root leak and NULL pointer dereference (bsc#1188325).
  • btrfs: relocation: fix reloc_root lifespan and access (bsc#1188325).
  • config: disable unprivileged BPF by default (jsc#SLE-22918) Backport of mainline commit 8a03e56b253e ("bpf: Disallow unprivileged bpf by default") only changes kconfig default, used e.g. for "make oldconfig" when the config option is missing, but does not update our kernel configs used for build. Update also these to make sure unprivileged BPF is really disabled by default.
  • kABI: protect struct bpf_map (kabi).
  • s390/bpf: Fix 64-bit subtraction of the -0x80000000 constant (bsc#1190601).
  • s390/bpf: Fix branch shortening during codegen pass (bsc#1190601).
  • s390/bpf: Fix optimizing out zero-extensions (bsc#1190601).
  • s390/bpf: Wrap JIT macro parameter usages in parentheses (bsc#1190601).
  • s390: bpf: implement jitting of BPF_ALU | BPF_ARSH | BPF_* (bsc#1190601).
  • scsi: sg: add sg_remove_request in sg_write (bsc#1171420 CVE2020-12770).
  • sctp: check asoc peer.asconf_capable before processing asconf (bsc#1190351).
  • sctp: fully initialize v4 addr in some functions (bsc#1188563).
  • sctp: simplify addr copy (bsc#1188563).

Special Instructions and Notes:

Please reboot the system after installing this update.

Patch Instructions:

To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Alternatively you can run the command listed for your product:

  • SUSE Linux Enterprise Server 12-SP2-BCL:
    zypper in -t patch SUSE-SLE-SERVER-12-SP2-BCL-2021-3929=1

Package List:

  • SUSE Linux Enterprise Server 12-SP2-BCL (noarch):
    • kernel-devel-4.4.121-92.161.1
    • kernel-macros-4.4.121-92.161.1
    • kernel-source-4.4.121-92.161.1
  • SUSE Linux Enterprise Server 12-SP2-BCL (x86_64):
    • kernel-default-4.4.121-92.161.1
    • kernel-default-base-4.4.121-92.161.1
    • kernel-default-base-debuginfo-4.4.121-92.161.1
    • kernel-default-debuginfo-4.4.121-92.161.1
    • kernel-default-debugsource-4.4.121-92.161.1
    • kernel-default-devel-4.4.121-92.161.1
    • kernel-syms-4.4.121-92.161.1