Fixed
Created: Aug 7, 2024
Updated: Sep 15, 2024
Resolved Date: Aug 7, 2024
Found In Version: 10.23.30.1
Fix Version: 10.23.30.13
Severity: Standard
Applicable for: Wind River Linux LTS 23
Component/s: Kernel
In the Linux kernel, the following vulnerability has been resolved:x86/bhi: Avoid warning in #DB handler due to BHI mitigationWhen BHI mitigation is enabled, if SYSENTER is invoked with the TF flag setthen entry_SYSENTER_compat() uses CLEAR_BRANCH_HISTORY and calls theclear_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 theentry_SYSENTER_compat() function.To address this issue, entry_SYSENTER_compat() should use CLEAR_BRANCH_HISTORYafter 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. ]
CREATE(Triage):(User=admin) [CVE-2024-42240 (https://nvd.nist.gov/vuln/detail/CVE-2024-42240)
