{ "id": "CVE-2024-42240", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2024-08-07T16:15:46.810", "lastModified": "2024-08-08T14:53:59.897", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/bhi: Avoid warning in #DB handler due to BHI mitigation\n\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.\n\nTo address this issue, entry_SYSENTER_compat() should use CLEAR_BRANCH_HISTORY\nafter making sure the TF flag is cleared.\n\nThe problem can be reproduced with the following sequence:\n\n $ cat sysenter_step.c\n int main()\n { asm(\"pushf; pop %ax; bts $8,%ax; push %ax; popf; sysenter\"); }\n\n $ gcc -o sysenter_step sysenter_step.c\n\n $ ./sysenter_step\n Segmentation fault (core dumped)\n\nThe program is expected to crash, and the #DB handler will issue a warning.\n\nKernel log:\n\n WARNING: CPU: 27 PID: 7000 at arch/x86/kernel/traps.c:1009 exc_debug_kernel+0xd2/0x160\n ...\n RIP: 0010:exc_debug_kernel+0xd2/0x160\n ...\n Call 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\n exc_debug+0x43/0x50\n asm_exc_debug+0x1e/0x40\n RIP: 0010:clear_bhb_loop+0x0/0xb0\n ...\n \n \n ? entry_SYSENTER_compat_after_hwframe+0x6e/0x8d\n \n\n [ bp: Massage commit message. ]" }, { "lang": "es", "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: x86/bhi: evitar advertencia en el controlador #DB debido a la mitigaci\u00f3n de BHI Cuando la mitigaci\u00f3n de BHI est\u00e1 habilitada, si se invoca SYSENTER con el indicador TF configurado, entonces Entry_SYSENTER_compat() usa CLEAR_BRANCH_HISTORY y llama al clear_bhb_loop() antes de que se borre la bandera TF. Esto hace que el controlador #DB (exc_debug_kernel()) emita una advertencia porque se utiliza un solo paso fuera de la funci\u00f3n Entry_SYSENTER_compat(). Para solucionar este problema, Entry_SYSENTER_compat() debe usar CLEAR_BRANCH_HISTORY despu\u00e9s de asegurarse de que el indicador TF est\u00e9 borrado. El problema se puede reproducir con la siguiente secuencia: $ 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 Fallo de segmentaci\u00f3n (n\u00facleo volcado) Se espera que el programa falle y el controlador #DB emitir\u00e1 una advertencia. Registro del kernel: ADVERTENCIA: CPU: 27 PID: 7000 en arch/x86/kernel/traps.c:1009 exc_debug_kernel+0xd2/0x160... RIP: 0010:exc_debug_kernel+0xd2/0x160... Seguimiento de llamadas: <#DB> ? show_regs+0x68/0x80? __advertir+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 ... ? Entry_SYSENTER_compat_after_hwframe+0x6e/0x8d [bp: mensaje de commit de masaje. ]" } ], "metrics": { "cvssMetricV31": [ { "source": "nvd@nist.gov", "type": "Primary", "cvssData": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM" }, "exploitabilityScore": 1.8, "impactScore": 3.6 } ] }, "weaknesses": [ { "source": "nvd@nist.gov", "type": "Primary", "description": [ { "lang": "en", "value": "CWE-835" } ] } ], "configurations": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.163", "versionEndExcluding": "6.1.100", "matchCriteriaId": "CAAB30CE-506C-42CC-B146-52655F61012E" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.41", "matchCriteriaId": "96AC42B8-D66D-4AC5-B466-E9BA7910FA29" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.9.10", "matchCriteriaId": "AB2E8DEC-CFD5-4C2B-981D-E7E45A36C352" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/08518d48e5b744620524f0acd7c26c19bda7f513", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/a765679defe1dc1b8fa01928a6ad6361e72a1364", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/ac8b270b61d48fcc61f052097777e3b5e11591e0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/db56615e96c439e13783d7715330e824b4fd4b84", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] } ] }