CVE-2024-42240

CVE Details

Release Date:

2024-08-07

Description

In the Linux kernel, the following vulnerability has been resolved:\nx86/bhi: Avoid warning in #DB handler due to BHI mitigation\nWhen BHI mitigation is enabled, if SYSENTER is invoked with the TF flag set\nthen entry_SYSENTER_compat() uses CLEAR_BRANCH_HISTORY and calls the\nclear_bhb_loop() before the TF flag is cleared. This causes the #DB handler\n(exc_debug_kernel()) to issue a warning because single-step is used outside the\nentry_SYSENTER_compat() function.\nTo address this issue, entry_SYSENTER_compat() should use CLEAR_BRANCH_HISTORY\nafter making sure the TF flag is cleared.\nThe problem can be reproduced with the following sequence:\n$ cat sysenter_step.c\nint main()\n{ asm('pushf; pop %ax; bts ,%ax; push %ax; popf; sysenter'); }\n$ gcc -o sysenter_step sysenter_step.c\n$ ./sysenter_step\nSegmentation fault (core dumped)\nThe program is expected to crash, and the #DB handler will issue a warning.\nKernel log:\nWARNING: CPU: 27 PID: 7000 at arch/x86/kernel/traps.c:1009 exc_debug_kernel+0xd2/0x160\n...\nRIP: 0010:exc_debug_kernel+0xd2/0x160\n...\nCall Trace:\n<#DB>\n? show_regs+0x68/0x80\n? __warn+0x8c/0x140\n? exc_debug_kernel+0xd2/0x160\n? report_bug+0x175/0x1a0\n? handle_bug+0x44/0x90\n? exc_invalid_op+0x1c/0x70\n? asm_exc_invalid_op+0x1f/0x30\n? exc_debug_kernel+0xd2/0x160\nexc_debug+0x43/0x50\nasm_exc_debug+0x1e/0x40\nRIP: 0010:clear_bhb_loop+0x0/0xb0\n...\n\n\n? entry_SYSENTER_compat_after_hwframe+0x6e/0x8d\n\n[ bp: Massage commit message. ]

See more information about CVE-2024-42240 from MITRE CVE dictionary and NIST NVD

CVSS Scoring

NOTE: The following CVSS v3.1 metrics and score provided are preliminary and subject to review.

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

Errata information

Platform	Errata	Release Date
Oracle Linux version 8 (kernel)	ELSA-2024-7000	2024-09-24
Oracle Linux version 9 (kernel)	ELSA-2024-9315	2024-11-14