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Fencer Vulns
medium 5.5

CVE-2024-42240 json

x86/bhi: Avoid warning in #DB handler due to BHI mitigation

published 2024-08-07 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-39463

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

x86/bhi: Avoid warning in #DB handler due to BHI mitigation

When BHI mitigation is enabled, if SYSENTER is invoked with the TF flag set then entry_SYSENTER_compat() uses CLEAR_BRANCH_HISTORY and calls the clear_bhb_loop() before the TF flag is cleared. This causes the #DB handler (exc_debug_kernel()) to issue a warning because single-step is used outside the entry_SYSENTER_compat() function.

To address this issue, entry_SYSENTER_compat() should use CLEAR_BRANCH_HISTORY after making sure the TF flag is cleared.

The problem can be reproduced with the following sequence:

$ cat sysenter_step.c int main() { asm("pushf; pop %ax; bts $8,%ax; push %ax; popf; sysenter"); }

$ gcc -o sysenter_step sysenter_step.c

$ ./sysenter_step Segmentation fault (core dumped)

The program is expected to crash, and the #DB handler will issue a warning.

Kernel log:

WARNING: CPU: 27 PID: 7000 at arch/x86/kernel/traps.c:1009 exc_debug_kernel+0xd2/0x160 ... RIP: 0010:exc_debug_kernel+0xd2/0x160 ... Call Trace: <#DB> ? show_regs+0x68/0x80 ? __warn+0x8c/0x140 ? exc_debug_kernel+0xd2/0x160 ? report_bug+0x175/0x1a0 ? handle_bug+0x44/0x90 ? exc_invalid_op+0x1c/0x70 ? asm_exc_invalid_op+0x1f/0x30 ? exc_debug_kernel+0xd2/0x160 exc_debug+0x43/0x50 asm_exc_debug+0x1e/0x40 RIP: 0010:clear_bhb_loop+0x0/0xb0 ... </#DB> <TASK> ? entry_SYSENTER_compat_after_hwframe+0x6e/0x8d </TASK>

[ bp: Massage commit message. ]

Patch / fix

  • Linux Linux 5.15.163, 6.1.100, 6.6.41, 6.9, 6.9.10, 6.10
  • linux Debian 12 6.1.106-1
  • linux Debian 14, Debian 13 6.9.10-1

debian advisories DEBIAN-CVE-2024-42240

  • linux Ubuntu 20.04 LTS 5.4.0-202.222
  • linux Ubuntu 22.04 LTS 5.15.0-121.131
  • linux Ubuntu 24.04 LTS 6.8.0-48.48
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1136.146
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1069.75
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1018.20
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1140.149
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1068.76

ubuntu advisories UBUNTU-CVE-2024-42240

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-503.11.1.el9_5
  • rv RHEL 9 5.14.0-503.11.1.el9_5
  • perf RHEL 9 5.14.0-503.11.1.el9_5
  • rtla RHEL 9 5.14.0-503.11.1.el9_5
  • bpftool RHEL 9 7.4.0-503.11.1.el9_5
  • libperf RHEL 9 5.14.0-503.11.1.el9_5
  • kernel-rt RHEL 9 5.14.0-503.11.1.el9_5
  • kernel-64k RHEL 9 5.14.0-503.11.1.el9_5

red hat advisories RHSA-2024:10773RHSA-2024:10772RHSA-2024:10771RHSA-2024:9315RHSA-2024:7000RHSA-2024:7001

  • kernel-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.115.1
  • kernel-source-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.115.1
  • kernel-64kb SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS, SLE High Performance Computing 15 SP4-ESPOS 5.14.21-150400.24.158.1
  • kernel-syms SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +3 more 5.14.21-150400.24.158.1
  • kernel-source SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +3 more 5.14.21-150400.24.158.1
  • kernel-default SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +7 more 5.14.21-150400.24.158.1
  • kernel-zfcpdump SLES 15 SP4-LTSS, Manager Server 4.3 5.14.21-150400.24.158.1
  • kernel-obs-build SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 5.14.21-150400.24.158.1

suse advisories SUSE-SU-2025:1183-1SUSE-SU-2025:1027-1SUSE-SU-2025:20047-1SUSE-SU-2025:20044-1SUSE-SU-2024:3483-1SUSE-SU-2024:3383-1

  • kernel AlmaLinux 8 4.18.0-553.22.1.el8_10
  • perf AlmaLinux 8 4.18.0-553.22.1.el8_10
  • bpftool AlmaLinux 8 4.18.0-553.22.1.el8_10
  • kernel-core AlmaLinux 8 4.18.0-553.22.1.el8_10
  • kernel-tools AlmaLinux 8 4.18.0-553.22.1.el8_10
  • python3-perf AlmaLinux 8 4.18.0-553.22.1.el8_10
  • kernel-modules AlmaLinux 8 4.18.0-553.22.1.el8_10
  • kernel-zfcpdump AlmaLinux 8 4.18.0-553.22.1.el8_10

almalinux advisories ALSA-2024:7000ALSA-2024:7001

  • kernel Rocky Linux 8 4.18.0-553.22.1.el8_10
  • kernel-rt Rocky Linux 8 4.18.0-553.22.1.rt7.363.el8_10

rocky linux advisories RLSA-2024:7000RLSA-2024:7001

  • kernel Azure Linux 3.0 6.6.43.1-7
  • kernel CBL-Mariner 2.0 5.15.167.1-1

azure linux advisories AZL-47528AZL-47791

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-42240 updated cvss 5.5

kernel: x86/bhi: Avoid warning in #DB handler due to BHI mitigation

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix planned “Will not fix”
  • Red Hat CodeReady Linux Builder (v. 9) libperf 5.14.0-503.11.1.el9_5, kernel-debuginfo-common-s390x 5.14.0-503.11.1.el9_5, kernel-debuginfo-common-x86_64 5.14.0-503.11.1.el9_5, kernel-debuginfo-common-aarch64 5.14.0-503.11.1.el9_5, kernel-debuginfo-common-ppc64le 5.14.0-503.11.1.el9_5
    fixed: vendor fix RHSA-2024:9315
  • Red Hat CodeReady Linux Builder EUS (v.9.2) kernel-debuginfo-common-s390x 5.14.0-284.95.1.el9_2, kernel-debuginfo-common-x86_64 5.14.0-284.95.1.el9_2, kernel-debuginfo-common-aarch64 5.14.0-284.95.1.el9_2, kernel-debuginfo-common-ppc64le 5.14.0-284.95.1.el9_2
    fixed: vendor fix RHSA-2024:10772
  • Red Hat CodeReady Linux Builder EUS (v.9.4) libperf 5.14.0-427.47.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.47.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.47.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.47.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.47.1.el9_4
    fixed: vendor fix RHSA-2024:10771
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-503.11.1.el9_5, perf 5.14.0-503.11.1.el9_5, rtla 5.14.0-503.11.1.el9_5, kernel-devel-matched 5.14.0-503.11.1.el9_5, kernel-64k-devel-matched 5.14.0-503.11.1.el9_5, kernel-debug-devel-matched 5.14.0-503.11.1.el9_5, +6 more
    fixed: vendor fix RHSA-2024:9315
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) perf 5.14.0-284.95.1.el9_2, rtla 5.14.0-284.95.1.el9_2, kernel-devel-matched 5.14.0-284.95.1.el9_2, kernel-64k-devel-matched 5.14.0-284.95.1.el9_2, kernel-debug-devel-matched 5.14.0-284.95.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.95.1.el9_2, +5 more
    fixed: vendor fix RHSA-2024:10772
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) rv 5.14.0-427.47.1.el9_4, perf 5.14.0-427.47.1.el9_4, rtla 5.14.0-427.47.1.el9_4, kernel-devel-matched 5.14.0-427.47.1.el9_4, kernel-64k-devel-matched 5.14.0-427.47.1.el9_4, kernel-debug-devel-matched 5.14.0-427.47.1.el9_4, +6 more
    fixed: vendor fix RHSA-2024:10771
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.22.1.el8_10, kernel 4.18.0-553.22.1.el8_10, bpftool 4.18.0-553.22.1.el8_10, kernel-core 4.18.0-553.22.1.el8_10, kernel-tools 4.18.0-553.22.1.el8_10, python3-perf 4.18.0-553.22.1.el8_10, +15 more
    fixed: vendor fix RHSA-2024:7000
show 14 more
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.4.0-503.11.1.el9_5, kernel 5.14.0-503.11.1.el9_5, kernel-64k 5.14.0-503.11.1.el9_5, kernel-core 5.14.0-503.11.1.el9_5, kernel-tools 5.14.0-503.11.1.el9_5, python3-perf 5.14.0-503.11.1.el9_5, +29 more
    fixed: vendor fix RHSA-2024:9315
  • Red Hat Enterprise Linux BaseOS EUS (v.9.2) bpftool 7.0.0-284.95.1.el9_2, kernel 5.14.0-284.95.1.el9_2, kernel-64k 5.14.0-284.95.1.el9_2, kernel-core 5.14.0-284.95.1.el9_2, kernel-tools 5.14.0-284.95.1.el9_2, python3-perf 5.14.0-284.95.1.el9_2, +28 more
    fixed: vendor fix RHSA-2024:10772
  • Red Hat Enterprise Linux BaseOS EUS (v.9.4) bpftool 7.3.0-427.47.1.el9_4, kernel 5.14.0-427.47.1.el9_4, kernel-64k 5.14.0-427.47.1.el9_4, kernel-core 5.14.0-427.47.1.el9_4, kernel-tools 5.14.0-427.47.1.el9_4, python3-perf 5.14.0-427.47.1.el9_4, +28 more
    fixed: vendor fix RHSA-2024:10771
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.22.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.22.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.22.1.el8_10
    fixed: vendor fix RHSA-2024:7000
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-kvm 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-kvm 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-core 4.18.0-553.22.1.rt7.363.el8_10, +4 more
    fixed: vendor fix RHSA-2024:7001
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-503.11.1.el9_5, kernel-rt-core 5.14.0-503.11.1.el9_5, kernel-rt-modules 5.14.0-503.11.1.el9_5, kernel-rt-debug-core 5.14.0-503.11.1.el9_5, kernel-rt-modules-core 5.14.0-503.11.1.el9_5, kernel-rt-debug-modules 5.14.0-503.11.1.el9_5, +4 more
    fixed: vendor fix RHSA-2024:9315
  • Red Hat Enterprise Linux Real Time EUS (v.9.2) kernel-rt 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-core 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-modules 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-debug-core 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-modules-core 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-debug-modules 5.14.0-284.95.1.rt14.380.el9_2, +4 more
    fixed: vendor fix RHSA-2024:10773
  • Red Hat Enterprise Linux Real Time EUS (v.9.4) kernel-rt 5.14.0-427.47.1.el9_4, kernel-rt-core 5.14.0-427.47.1.el9_4, kernel-rt-modules 5.14.0-427.47.1.el9_4, kernel-rt-debug-core 5.14.0-427.47.1.el9_4, kernel-rt-modules-core 5.14.0-427.47.1.el9_4, kernel-rt-debug-modules 5.14.0-427.47.1.el9_4, +4 more
    fixed: vendor fix RHSA-2024:10771
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-503.11.1.el9_5, kernel-rt-kvm 5.14.0-503.11.1.el9_5, kernel-rt-core 5.14.0-503.11.1.el9_5, kernel-rt-modules 5.14.0-503.11.1.el9_5, kernel-rt-debug-kvm 5.14.0-503.11.1.el9_5, kernel-rt-debug-core 5.14.0-503.11.1.el9_5, +6 more
    fixed: vendor fix RHSA-2024:9315
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.2) kernel-rt 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-kvm 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-core 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-modules 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-debug-kvm 5.14.0-284.95.1.rt14.380.el9_2, kernel-rt-debug-core 5.14.0-284.95.1.rt14.380.el9_2, +6 more
    fixed: vendor fix RHSA-2024:10773
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) kernel-rt 5.14.0-427.47.1.el9_4, kernel-rt-kvm 5.14.0-427.47.1.el9_4, kernel-rt-core 5.14.0-427.47.1.el9_4, kernel-rt-modules 5.14.0-427.47.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.47.1.el9_4, kernel-rt-debug-core 5.14.0-427.47.1.el9_4, +6 more
    fixed: vendor fix RHSA-2024:10771
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-core 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-debug-modules 4.18.0-553.22.1.rt7.363.el8_10, kernel-rt-modules-extra 4.18.0-553.22.1.rt7.363.el8_10, +2 more
    fixed: vendor fix RHSA-2024:7001
  • Red Hat OpenShift AI 8 rhoai/odh-rhel8-operator v2.13.1-2, rhoai/odh-dashboard-rhel8 v2.13.1-1, rhoai/odh-modelmesh-rhel8 v2.13.1-1, rhoai/odh-operator-bundle v2.13.1-2, rhoai/odh-rhel8-operator v2.14.0-24, rhoai/odh-dashboard-rhel8 v2.14.0-11, +56 more
    fixed: vendor fix RHBA-2024:8413
  • Red Hat CodeReady Linux Builder (v. 9) kernel-cross-headers 5.14.0-503.11.1.el9_5 Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux AppStream (v. 9) kernel-headers 5.14.0-503.11.1.el9_5 Red Hat Enterprise Linux AppStream EUS (v.9.2) kernel-doc 5.14.0-284.95.1.el9_2
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.