ghsa-g8c8-mwvp-jcrr
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
powerpc/64s: Fix unrecoverable MCE calling async handler from NMI
The machine check handler is not considered NMI on 64s. The early handler is the true NMI handler, and then it schedules the machine_check_exception handler to run when interrupts are enabled.
This works fine except the case of an unrecoverable MCE, where the true NMI is taken when MSR[RI] is clear, it can not recover, so it calls machine_check_exception directly so something might be done about it.
Calling an async handler from NMI context can result in irq state and other things getting corrupted. This can also trigger the BUG at arch/powerpc/include/asm/interrupt.h:168 BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));
Fix this by making an _async version of the handler which is called in the normal case, and a NMI version that is called for unrecoverable interrupts.
{
"affected": [],
"aliases": [
"CVE-2021-47429"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-21T15:15:28Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/64s: Fix unrecoverable MCE calling async handler from NMI\n\nThe machine check handler is not considered NMI on 64s. The early\nhandler is the true NMI handler, and then it schedules the\nmachine_check_exception handler to run when interrupts are enabled.\n\nThis works fine except the case of an unrecoverable MCE, where the true\nNMI is taken when MSR[RI] is clear, it can not recover, so it calls\nmachine_check_exception directly so something might be done about it.\n\nCalling an async handler from NMI context can result in irq state and\nother things getting corrupted. This can also trigger the BUG at\n arch/powerpc/include/asm/interrupt.h:168\n BUG_ON(!arch_irq_disabled_regs(regs) \u0026\u0026 !(regs-\u003emsr \u0026 MSR_EE));\n\nFix this by making an _async version of the handler which is called\nin the normal case, and a NMI version that is called for unrecoverable\ninterrupts.",
"id": "GHSA-g8c8-mwvp-jcrr",
"modified": "2024-05-21T15:31:45Z",
"published": "2024-05-21T15:31:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47429"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d7a8e38999fbd6910516e44cb43f9f4317e54f73"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f08fb25bc66986b0952724530a640d9970fa52c1"
}
],
"schema_version": "1.4.0",
"severity": []
}