{
    "data_version": "4.0",
    "data_type": "CVE",
    "data_format": "MITRE",
    "CVE_data_meta": {
        "ID": "CVE-2023-52761",
        "ASSIGNER": "cve@kernel.org",
        "STATE": "PUBLIC"
    },
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: VMAP_STACK overflow detection thread-safe\n\ncommit 31da94c25aea (\"riscv: add VMAP_STACK overflow detection\") added\nsupport for CONFIG_VMAP_STACK. If overflow is detected, CPU switches to\n`shadow_stack` temporarily before switching finally to per-cpu\n`overflow_stack`.\n\nIf two CPUs/harts are racing and end up in over flowing kernel stack, one\nor both will end up corrupting each other state because `shadow_stack` is\nnot per-cpu. This patch optimizes per-cpu overflow stack switch by\ndirectly picking per-cpu `overflow_stack` and gets rid of `shadow_stack`.\n\nFollowing are the changes in this patch\n\n - Defines an asm macro to obtain per-cpu symbols in destination\n   register.\n - In entry.S, when overflow is detected, per-cpu overflow stack is\n   located using per-cpu asm macro. Computing per-cpu symbol requires\n   a temporary register. x31 is saved away into CSR_SCRATCH\n   (CSR_SCRATCH is anyways zero since we're in kernel).\n\nPlease see Links for additional relevant disccussion and alternative\nsolution.\n\nTested by `echo EXHAUST_STACK > /sys/kernel/debug/provoke-crash/DIRECT`\nKernel crash log below\n\n Insufficient stack space to handle exception!/debug/provoke-crash/DIRECT\n Task stack:     [0xff20000010a98000..0xff20000010a9c000]\n Overflow stack: [0xff600001f7d98370..0xff600001f7d99370]\n CPU: 1 PID: 205 Comm: bash Not tainted 6.1.0-rc2-00001-g328a1f96f7b9 #34\n Hardware name: riscv-virtio,qemu (DT)\n epc : __memset+0x60/0xfc\n  ra : recursive_loop+0x48/0xc6 [lkdtm]\n epc : ffffffff808de0e4 ra : ffffffff0163a752 sp : ff20000010a97e80\n  gp : ffffffff815c0330 tp : ff600000820ea280 t0 : ff20000010a97e88\n  t1 : 000000000000002e t2 : 3233206874706564 s0 : ff20000010a982b0\n  s1 : 0000000000000012 a0 : ff20000010a97e88 a1 : 0000000000000000\n  a2 : 0000000000000400 a3 : ff20000010a98288 a4 : 0000000000000000\n  a5 : 0000000000000000 a6 : fffffffffffe43f0 a7 : 00007fffffffffff\n  s2 : ff20000010a97e88 s3 : ffffffff01644680 s4 : ff20000010a9be90\n  s5 : ff600000842ba6c0 s6 : 00aaaaaac29e42b0 s7 : 00fffffff0aa3684\n  s8 : 00aaaaaac2978040 s9 : 0000000000000065 s10: 00ffffff8a7cad10\n  s11: 00ffffff8a76a4e0 t3 : ffffffff815dbaf4 t4 : ffffffff815dbaf4\n  t5 : ffffffff815dbab8 t6 : ff20000010a9bb48\n status: 0000000200000120 badaddr: ff20000010a97e88 cause: 000000000000000f\n Kernel panic - not syncing: Kernel stack overflow\n CPU: 1 PID: 205 Comm: bash Not tainted 6.1.0-rc2-00001-g328a1f96f7b9 #34\n Hardware name: riscv-virtio,qemu (DT)\n Call Trace:\n [<ffffffff80006754>] dump_backtrace+0x30/0x38\n [<ffffffff808de798>] show_stack+0x40/0x4c\n [<ffffffff808ea2a8>] dump_stack_lvl+0x44/0x5c\n [<ffffffff808ea2d8>] dump_stack+0x18/0x20\n [<ffffffff808dec06>] panic+0x126/0x2fe\n [<ffffffff800065ea>] walk_stackframe+0x0/0xf0\n [<ffffffff0163a752>] recursive_loop+0x48/0xc6 [lkdtm]\n SMP: stopping secondary CPUs\n ---[ end Kernel panic - not syncing: Kernel stack overflow ]---"
            }
        ]
    },
    "problemtype": {
        "problemtype_data": [
            {
                "description": [
                    {
                        "lang": "eng",
                        "value": "n/a"
                    }
                ]
            }
        ]
    },
    "affects": {
        "vendor": {
            "vendor_data": [
                {
                    "vendor_name": "Linux",
                    "product": {
                        "product_data": [
                            {
                                "product_name": "Linux",
                                "version": {
                                    "version_data": [
                                        {
                                            "version_affected": "<",
                                            "version_name": "76d2a0493a17",
                                            "version_value": "1493baaf09e3"
                                        },
                                        {
                                            "version_value": "not down converted",
                                            "x_cve_json_5_version_data": {
                                                "versions": [
                                                    {
                                                        "version": "4.15",
                                                        "status": "affected"
                                                    },
                                                    {
                                                        "version": "0",
                                                        "lessThan": "4.15",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.5.13",
                                                        "lessThanOrEqual": "6.5.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.6.3",
                                                        "lessThanOrEqual": "6.6.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.7",
                                                        "lessThanOrEqual": "*",
                                                        "status": "unaffected",
                                                        "versionType": "original_commit_for_fix"
                                                    }
                                                ],
                                                "defaultStatus": "affected"
                                            }
                                        }
                                    ]
                                }
                            }
                        ]
                    }
                }
            ]
        }
    },
    "references": {
        "reference_data": [
            {
                "url": "https://git.kernel.org/stable/c/1493baaf09e3c1899959c8a107cd1207e16d1788",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/1493baaf09e3c1899959c8a107cd1207e16d1788"
            },
            {
                "url": "https://git.kernel.org/stable/c/eff53aea3855f71992c043cebb1c00988c17ee20",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/eff53aea3855f71992c043cebb1c00988c17ee20"
            },
            {
                "url": "https://git.kernel.org/stable/c/be97d0db5f44c0674480cb79ac6f5b0529b84c76",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/be97d0db5f44c0674480cb79ac6f5b0529b84c76"
            }
        ]
    },
    "generator": {
        "engine": "bippy-8e903de6a542"
    }
}