CVE-2021-31440

This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel 5.11.15. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the handling of eBPF programs. The issue results from the lack of proper validation of user-supplied eBPF programs prior to executing them. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel. Was ZDI-CAN-13661.

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

• kernel: out-of-bounds reads in pinctrl subsystem (CVE-2020-0427)
• kernel: Improper input validation in some Intel(R) Ethernet E810 Adapter drivers (CVE-2020-24502)
• kernel: Insufficient access control in some Intel(R) Ethernet E810 Adapter drivers (CVE-2020-24503)
• kernel: Uncontrolled resource consumption in some Intel(R) Ethernet E810 Adapter drivers (CVE-2020-24504)
• kernel: Fragmentation cache not cleared on reconnection (CVE-2020-24586)
• kernel: Reassembling fragments encrypted under different keys (CVE-2020-24587)
• kernel: wifi frame payload being parsed incorrectly as an L2 frame (CVE-2020-24588)
• kernel: Forwarding EAPOL from unauthenticated wifi client (CVE-2020-26139)
• kernel: accepting plaintext data frames in protected networks (CVE-2020-26140)
• kernel: not verifying TKIP MIC of fragmented frames (CVE-2020-26141)
• kernel: accepting fragmented plaintext frames in protected networks (CVE-2020-26143)
• kernel: accepting unencrypted A-MSDU frames that start with RFC1042 header (CVE-2020-26144)
• kernel: accepting plaintext broadcast fragments as full frames (CVE-2020-26145)
• kernel: powerpc: RTAS calls can be used to compromise kernel integrity (CVE-2020-27777)
• kernel: locking inconsistency in tty_io.c and tty_jobctrl.c can lead to a read-after-free (CVE-2020-29660)
• kernel: buffer overflow in mwifiex_cmd_802_11_ad_hoc_start function via a long SSID value (CVE-2020-36158)
• kernel: slab out-of-bounds read in hci_extended_inquiry_result_evt() (CVE-2020-36386)
• kernel: Improper access control in BlueZ may allow information disclosure vulnerability. (CVE-2021-0129)
• kernel: Use-after-free in ndb_queue_rq() in drivers/block/nbd.c (CVE-2021-3348)
• kernel: Linux kernel eBPF RINGBUF map oversized allocation (CVE-2021-3489)
• kernel: double free in bluetooth subsystem when the HCI device initialization fails (CVE-2021-3564)
• kernel: use-after-free in function hci_sock_bound_ioctl() (CVE-2021-3573)
• kernel: eBPF 32-bit source register truncation on div/mod (CVE-2021-3600)
• kernel: DoS in rb_per_cpu_empty() (CVE-2021-3679)
• kernel: Mounting overlayfs inside an unprivileged user namespace can reveal files (CVE-2021-3732)
• kernel: heap overflow in __cgroup_bpf_run_filter_getsockopt() (CVE-2021-20194)
• kernel: Race condition in sctp_destroy_sock list_del (CVE-2021-23133)
• kernel: fuse: stall on CPU can occur because a retry loop continually finds the same bad inode (CVE-2021-28950)
• kernel: System crash in intel_pmu_drain_pebs_nhm in arch/x86/events/intel/ds.c (CVE-2021-28971)
• kernel: protection can be bypassed to leak content of kernel memory (CVE-2021-29155)
• kernel: improper input validation in tipc_nl_retrieve_key function in net/tipc/node.c (CVE-2021-29646)
• kernel: lack a full memory barrier may lead to DoS (CVE-2021-29650)
• kernel: local escalation of privileges in handling of eBPF programs (CVE-2021-31440)
• kernel: protection of stack pointer against speculative pointer arithmetic can be bypassed to leak content of kernel memory (CVE-2021-31829)
• kernel: out-of-bounds reads and writes due to enforcing incorrect limits for pointer arithmetic operations by BPF verifier (CVE-2021-33200)
• kernel: reassembling encrypted fragments with non-consecutive packet numbers (CVE-2020-26146)
• kernel: reassembling mixed encrypted/plaintext fragments (CVE-2020-26147)
• kernel: the copy-on-write implementation can grant unintended write access because of a race condition in a THP mapcount check (CVE-2020-29368)
• kernel: flowtable list del corruption with kernel BUG at lib/list_debug.c:50 (CVE-2021-3635)
• kernel: NULL pointer dereference in llsec_key_alloc() in net/mac802154/llsec.c (CVE-2021-3659)
• kernel: setsockopt System Call Untrusted Pointer Dereference Information Disclosure (CVE-2021-20239)
• kernel: out of bounds array access in drivers/md/dm-ioctl.c (CVE-2021-31916)

• tipc: improve size validations for received domain records (Jon Maloy) {CVE-2022-0435}
• bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds (Yauheni Kaliuta) {CVE-2021-31440}
• bpf: Fix propagation of 32-bit signed bounds from 64-bit bounds (Yauheni Kaliuta) {CVE-2021-31440}

This kernel update is based on upstream 5.10.37 and fixes at least the following security issues:

It was discovered that the io_uring implementation of the Linux kernel did not properly enforce the MAX_RW_COUNT limit in some situations. A local attacker could use this to cause a denial of service (system crash) or execute arbitrary code (CVE-2021-3491).

An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information (CVE-2021-3506).

A race condition in Linux kernel SCTP sockets (net/sctp/socket.c) before 5.12-rc8 can lead to kernel privilege escalation from the context of a network service or an unprivileged process. If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock then an element is removed from the auto_asconf_splist list without any proper locking. This can be exploited by an attacker with network service privileges to escalate to root or from the context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some SCTP socket. NOTE! This already had a fix in kernel-5.10.33, but that fix caused some systems to deadlock, so this is now fixed in a better way (CVE-2021-23133).

bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds (CVE-2021-31440).

kernel/bpf/verifier.c in the Linux kernel through 5.12.1 performs undesirable speculative loads, leading to disclosure of stack content via side-channel attacks. The specific concern is not protecting the BPF stack area against speculative loads. Also, the BPF stack can contain uninitialized data that might represent sensitive information previously operated on by the kernel (CVE-2021-31829).

net/bluetooth/hci_request.c in the Linux kernel through 5.12.2 has a race condition for removal of the HCI controller (CVE-2021-32399).

In the Linux kernel before 5.12.4, net/bluetooth/hci_event.c has a use-after-free when destroying an hci_chan. This leads to writing an arbitrary value. (CVE-2021-33034).

Other fixes in this update:

• Revert upstream iommu/vt-d fixes causing systems to hang at boot:
  • "iommu/vt-d: Preset Access/Dirty bits for IOVA over FL"
  • "iommu/vt-d: Remove WO permissions on second-level paging entries"
• Revert "irqbypass: do not start cons/prod when failed connect" as it may cause VM freeze on arm64 with GICv4
• ACPI / EC: Fix media keys not working problem on more Asus laptops
• ACPI: PM: Add ACPI ID of Alder Lake Fan
• iwlwifi: add new pci id for 6235
• usb: xhci: Add reset resume quirk for AMD xhci controller
• usb: xhci: Increase timeout for HC halt

For other upstream fixes, see the referenced changelogs.

This kernel-linus update is based on upstream 5.10.37 and fixes at least the following security issues:

It was discovered that the io_uring implementation of the Linux kernel did not properly enforce the MAX_RW_COUNT limit in some situations. A local attacker could use this to cause a denial of service (system crash) or execute arbitrary code (CVE-2021-3491).

An out-of-bounds (OOB) memory access flaw was found in fs/f2fs/node.c in the f2fs module in the Linux kernel in versions before 5.12.0-rc4. A bounds check failure allows a local attacker to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information (CVE-2021-3506).

A race condition in Linux kernel SCTP sockets (net/sctp/socket.c) before 5.12-rc8 can lead to kernel privilege escalation from the context of a network service or an unprivileged process. If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock then an element is removed from the auto_asconf_splist list without any proper locking. This can be exploited by an attacker with network service privileges to escalate to root or from the context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some SCTP socket. NOTE! This already had a fix in kernel-5.10.33, but that fix caused some systems to deadlock, so this is now fixed in a better way (CVE-2021-23133).

bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds (CVE-2021-31440).

kernel/bpf/verifier.c in the Linux kernel through 5.12.1 performs undesirable speculative loads, leading to disclosure of stack content via side-channel attacks. The specific concern is not protecting the BPF stack area against speculative loads. Also, the BPF stack can contain uninitialized data that might represent sensitive information previously operated on by the kernel (CVE-2021-31829).

net/bluetooth/hci_request.c in the Linux kernel through 5.12.2 has a race condition for removal of the HCI controller (CVE-2021-32399).

In the Linux kernel before 5.12.4, net/bluetooth/hci_event.c has a use-after-free when destroying an hci_chan. This leads to writing an arbitrary value. (CVE-2021-33034).

For other upstream fixes, see the referenced changelogs.

In __reg_combine_64_into_32 of verifier.c, there is a possible out of bounds write due to an integer overflow. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.

This update for the Linux Kernel 5.3.18-57 fixes several issues.

The following security issues were fixed:

• CVE-2021-31440: Fixed a lack of proper validation of user-supplied eBPF programs prior to executing them. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel. (bsc#1190127).
• CVE-2021-38160: Fixed a bug that could lead to a data corruption or loss. This can be triggered by an untrusted device that supplies a buf->len value exceeding the buffer size in drivers/char/virtio_console.c (bsc#1190118)
• CVE-2021-3640: Fixed a user-after-free bug in the function sco_sock_sendmsg which could lead to local privilege escalation. (bsc#1188613)
• CVE-2021-3573: Fixed a user-after-free bug in the function hci_sock_bound_ioctl which could lead to local privilege escalation. (bsc#1187054).

Norbert Slusarek discovered a race condition in the CAN BCM networking protocol of the Linux kernel leading to multiple use-after-free vulnerabilities. A local attacker could use this issue to execute arbitrary code. (CVE-2021-3609)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel did not properly enforce limits for pointer operations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-33200)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did not properly clear received fragments from memory in some situations. A physically proximate attacker could possibly use this issue to inject packets or expose sensitive information. (CVE-2020-24586)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation incorrectly handled encrypted fragments. A physically proximate attacker could possibly use this issue to decrypt fragments. (CVE-2020-24587)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation incorrectly handled certain malformed frames. If a user were tricked into connecting to a malicious server, a physically proximate attacker could use this issue to inject packets. (CVE-2020-24588)

Kiyin (尹亮) discovered that the NFC LLCP protocol implementation in the Linux kernel contained a reference counting error. A local attacker could use this to cause a denial of service (system crash). (CVE-2020-25670)

Kiyin (尹亮) discovered that the NFC LLCP protocol implementation in the Linux kernel did not properly deallocate memory in certain error situations. A local attacker could use this to cause a denial of service (memory exhaustion). (CVE-2020-25671, CVE-2020-25672)

Kiyin (尹亮) discovered that the NFC LLCP protocol implementation in the Linux kernel did not properly handle error conditions in some situations, leading to an infinite loop. A local attacker could use this to cause a denial of service. (CVE-2020-25673)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation incorrectly handled EAPOL frames from unauthenticated senders. A physically proximate attacker could inject malicious packets to cause a denial of service (system crash). (CVE-2020-26139)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did not properly verify certain fragmented frames. A physically proximate attacker could possibly use this issue to inject or decrypt packets. (CVE-2020-26141)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation accepted plaintext fragments in certain situations. A physically proximate attacker could use this issue to inject packets. (CVE-2020-26145)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation could reassemble mixed encrypted and plaintext fragments. A physically proximate attacker could possibly use this issue to inject packets or exfiltrate selected fragments. (CVE-2020-26147)

Or Cohen discovered that the SCTP implementation in the Linux kernel contained a race condition in some situations, leading to a use-after-free condition. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-23133)

Piotr Krysiuk and Benedict Schlueter discovered that the eBPF implementation in the Linux kernel performed out of bounds speculation on pointer arithmetic. A local attacker could use this to expose sensitive information. (CVE-2021-29155)

Manfred Paul discovered that the extended Berkeley Packet Filter (eBPF) implementation in the Linux kernel contained an out-of-bounds vulnerability. A local attacker could use this issue to execute arbitrary code. (CVE-2021-31440)

Piotr Krysiuk discovered that the eBPF implementation in the Linux kernel did not properly prevent speculative loads in certain situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2021-31829)

Norbert Slusarek discovered a race condition in the CAN BCM networking protocol of the Linux kernel leading to multiple use-after-free vulnerabilities. A local attacker could use this issue to execute arbitrary code. (CVE-2021-3609)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did not properly clear received fragments from memory in some situations. A physically proximate attacker could possibly use this issue to inject packets or expose sensitive information. (CVE-2020-24586)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation incorrectly handled encrypted fragments. A physically proximate attacker could possibly use this issue to decrypt fragments. (CVE-2020-24587)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation incorrectly handled certain malformed frames. If a user were tricked into connecting to a malicious server, a physically proximate attacker could use this issue to inject packets. (CVE-2020-24588)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation incorrectly handled EAPOL frames from unauthenticated senders. A physically proximate attacker could inject malicious packets to cause a denial of service (system crash). (CVE-2020-26139)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation did not properly verify certain fragmented frames. A physically proximate attacker could possibly use this issue to inject or decrypt packets. (CVE-2020-26141)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation accepted plaintext fragments in certain situations. A physically proximate attacker could use this issue to inject packets. (CVE-2020-26145)

Mathy Vanhoef discovered that the Linux kernel’s WiFi implementation could reassemble mixed encrypted and plaintext fragments. A physically proximate attacker could possibly use this issue to inject packets or exfiltrate selected fragments. (CVE-2020-26147)

Or Cohen discovered that the SCTP implementation in the Linux kernel contained a race condition in some situations, leading to a use-after-free condition. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-23133)

Or Cohen and Nadav Markus discovered a use-after-free vulnerability in the nfc implementation in the Linux kernel. A privileged local attacker could use this issue to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-23134)

Manfred Paul discovered that the extended Berkeley Packet Filter (eBPF) implementation in the Linux kernel contained an out-of-bounds vulnerability. A local attacker could use this issue to execute arbitrary code. (CVE-2021-31440)

It was discovered that a race condition in the kernel Bluetooth subsystem could lead to use-after-free of slab objects. An attacker could use this issue to possibly execute arbitrary code. (CVE-2021-32399)

It was discovered that a use-after-free existed in the Bluetooth HCI driver of the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-33034)

It was discovered that an out-of-bounds (OOB) memory access flaw existed in the f2fs module of the Linux kernel. A local attacker could use this issue to cause a denial of service (system crash). (CVE-2021-3506)

Mathias Krause discovered that a null pointer dereference existed in the Nitro Enclaves kernel driver of the Linux kernel. A local attacker could use this issue to cause a denial of service or possibly execute arbitrary code. (CVE-2021-3543)