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Loop with Unreachable Exit Condition ('Infinite Loop') Affecting kernel-zfcpdump-core package, versions <0:4.18.0-553.22.1.el8_10

Severity

 Recommended
high

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-ALMALINUX8-KERNELZFCPDUMPCORE-8095269
  • published25 Sept 2024
  • disclosed24 Sept 2024
Report a new vulnerability Found a mistake?

Introduced: 24 Sep 2024

CVE-2024-42240  (opens in a new tab)
CWE-835  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:8 kernel-zfcpdump-core to version 0:4.18.0-553.22.1.el8_10 or higher.
This issue was patched in ALSA-2024:7000.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-zfcpdump-core package and not the kernel-zfcpdump-core package as distributed by AlmaLinux. See How to fix? for AlmaLinux:8 relevant fixed versions and status.

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>

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