发布时间: 2024年9月3日
修改时间: 2024年9月14日
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. ]
| NVD | openEuler | |
|---|---|---|
| CVSS评分 | 5.5 | 5.5 |
| Attack Vector | Local | Local |
| Attack Complexity | Low | Low |
| Privileges Required | Low | Low |
| User Interaction | None | None |
| Scope | Unchanged | Unchanged |
| Confidentiality | None | None |
| Integrity | None | None |
| Availability | High | High |
| 公告名 | 概要 | 发布时间 |
|---|---|---|
| KylinSec-SA-2024-3595 | 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. ] | 2024年9月3日 |
| 产品 | 包 | 状态 |
|---|---|---|
| KY3.4-5A | kernel | Unaffected |
| KY3.5.2 | kernel | Unaffected |
| V6 | kernel | Fixed |
