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CVE-2024-42240— x86/bhi: Avoid warning in #DB handler due to BHI mitigation

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 x86/bhi 模块BHI缓解机制在处理SYSENTER调用时存在问题。当设置了TF标志位时，entry_SYSENTER_compat在清除TF标志位之前使用了CLEAR_BRANCH_HISTORY，导致DB处理器发出警告。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.22% · P12

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 17

VendorProduct Version RangeStatus
Linux Linux bd53ec80f21839cfd4d852a6088279d602d67e5b< db56615e96c439e13783d7715330e824b4fd4b84 affected
07dbb10f153f483e8249acebdffedf922e2ec2e1< a765679defe1dc1b8fa01928a6ad6361e72a1364 affected
eb36b0dce2138581bc6b5e39d0273cb4c96ded81< dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf affected
7390db8aea0d64e9deb28b8e1ce716f5020c7ee5< 08518d48e5b744620524f0acd7c26c19bda7f513 affected
7390db8aea0d64e9deb28b8e1ce716f5020c7ee5< ac8b270b61d48fcc61f052097777e3b5e11591e0 affected
8f51637712e4da5be410a1666f8aee0d86eef898 affected
5.15.154< 5.15.163 affected
6.1.85< 6.1.100 affected
… +9 more rows
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I. Basic Information for CVE-2024-42240

Vulnerability Information
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Vulnerability Title
x86/bhi: Avoid warning in #DB handler due to BHI mitigation
Source: CVE Program / CVE List V5
Vulnerability 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. ]
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 x86/bhi 模块BHI缓解机制在处理SYSENTER调用时存在问题。当设置了TF标志位时，entry_SYSENTER_compat在清除TF标志位之前使用了CLEAR_BRANCH_HISTORY，导致DB处理器发出警告。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux bd53ec80f21839cfd4d852a6088279d602d67e5b ~ db56615e96c439e13783d7715330e824b4fd4b84 -
Linux Linux 6.9 -

II. Public POCs for CVE-2024-42240

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III. Intelligence Information for CVE-2024-42240

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Patches & Fixes for CVE-2024-42240 (5)

Same Patch Batch · Linux · 2024-08-07 · 19 CVEs total

CVE-2024-42232 9.8 CRITICAL libceph: fix race between delayed_work() and ceph_monc_stop()
CVE-2024-42249 7.8 HIGH spi: don't unoptimize message in spi_async()
CVE-2024-42234 7.8 HIGH mm: fix crashes from deferred split racing folio migration
CVE-2024-42233 7.8 HIGH filemap: replace pte_offset_map() with pte_offset_map_nolock()
CVE-2024-42235 7.8 HIGH s390/mm: Add NULL pointer check to crst_table_free() base_crst_free()
CVE-2024-42236 7.8 HIGH usb: gadget: configfs: Prevent OOB read/write in usb_string_copy()
CVE-2024-42250 7.8 HIGH cachefiles: add missing lock protection when polling
CVE-2024-42247 7.5 HIGH wireguard: allowedips: avoid unaligned 64-bit memory accesses
CVE-2024-42242 mmc: sdhci: Fix max_seg_size for 64KiB PAGE_SIZE
CVE-2024-42237 firmware: cs_dsp: Validate payload length before processing block
CVE-2024-42238 firmware: cs_dsp: Return error if block header overflows file
CVE-2024-42239 bpf: Fail bpf_timer_cancel when callback is being cancelled
CVE-2024-42241 mm/shmem: disable PMD-sized page cache if needed
CVE-2024-42244 USB: serial: mos7840: fix crash on resume
CVE-2024-42243 mm/filemap: make MAX_PAGECACHE_ORDER acceptable to xarray
CVE-2024-42245 Revert "sched/fair: Make sure to try to detach at least one movable task"
CVE-2024-42246 net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup_socket
CVE-2024-42248 tty: serial: ma35d1: Add a NULL check for of_node

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-42240

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