CVE-2024-42240

MEDIUM EPSS 12.3%
Published Aug 7, 20241y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Aug 7, 2024 1y ago
Last Modified Jun 17, 2026 1w ago

Description

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. ]

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
12.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-835

Affected Products 3

VendorProductVersionRange
linuxlinux_kernel*≥5.15.163  –  <6.1.100
linuxlinux_kernel*≥6.2  –  <6.6.41
linuxlinux_kernel*≥6.7  –  <6.9.10

References 6

  • git.kernel.org https://git.kernel.org/stable/c/08518d48e5b744620524f0acd7c26c19bda7f513
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a765679defe1dc1b8fa01928a6ad6361e72a1364
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ac8b270b61d48fcc61f052097777e3b5e11591e0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/db56615e96c439e13783d7715330e824b4fd4b84
    Patch
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/08518d48e5b744620524f0acd7c26c19bda7f513
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a765679defe1dc1b8fa01928a6ad6361e72a1364
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ac8b270b61d48fcc61f052097777e3b5e11591e0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/db56615e96c439e13783d7715330e824b4fd4b84
    Patch