cvelist/2024/39xxx/CVE-2024-39488.json

{
    "data_version": "4.0",
    "data_type": "CVE",
    "data_format": "MITRE",
    "CVE_data_meta": {
        "ID": "CVE-2024-39488",
        "ASSIGNER": "cve@kernel.org",
        "STATE": "PUBLIC"
    },
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: asm-bug: Add .align 2 to the end of __BUG_ENTRY\n\nWhen CONFIG_DEBUG_BUGVERBOSE=n, we fail to add necessary padding bytes\nto bug_table entries, and as a result the last entry in a bug table will\nbe ignored, potentially leading to an unexpected panic(). All prior\nentries in the table will be handled correctly.\n\nThe arm64 ABI requires that struct fields of up to 8 bytes are\nnaturally-aligned, with padding added within a struct such that struct\nare suitably aligned within arrays.\n\nWhen CONFIG_DEBUG_BUGVERPOSE=y, the layout of a bug_entry is:\n\n\tstruct bug_entry {\n\t\tsigned int      bug_addr_disp;\t// 4 bytes\n\t\tsigned int      file_disp;\t// 4 bytes\n\t\tunsigned short  line;\t\t// 2 bytes\n\t\tunsigned short  flags;\t\t// 2 bytes\n\t}\n\n... with 12 bytes total, requiring 4-byte alignment.\n\nWhen CONFIG_DEBUG_BUGVERBOSE=n, the layout of a bug_entry is:\n\n\tstruct bug_entry {\n\t\tsigned int      bug_addr_disp;\t// 4 bytes\n\t\tunsigned short  flags;\t\t// 2 bytes\n\t\t< implicit padding >\t\t// 2 bytes\n\t}\n\n... with 8 bytes total, with 6 bytes of data and 2 bytes of trailing\npadding, requiring 4-byte alginment.\n\nWhen we create a bug_entry in assembly, we align the start of the entry\nto 4 bytes, which implicitly handles padding for any prior entries.\nHowever, we do not align the end of the entry, and so when\nCONFIG_DEBUG_BUGVERBOSE=n, the final entry lacks the trailing padding\nbytes.\n\nFor the main kernel image this is not a problem as find_bug() doesn't\ndepend on the trailing padding bytes when searching for entries:\n\n\tfor (bug = __start___bug_table; bug < __stop___bug_table; ++bug)\n\t\tif (bugaddr == bug_addr(bug))\n\t\t\treturn bug;\n\nHowever for modules, module_bug_finalize() depends on the trailing\nbytes when calculating the number of entries:\n\n\tmod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);\n\n... and as the last bug_entry lacks the necessary padding bytes, this entry\nwill not be counted, e.g. in the case of a single entry:\n\n\tsechdrs[i].sh_size == 6\n\tsizeof(struct bug_entry) == 8;\n\n\tsechdrs[i].sh_size / sizeof(struct bug_entry) == 0;\n\nConsequently module_find_bug() will miss the last bug_entry when it does:\n\n\tfor (i = 0; i < mod->num_bugs; ++i, ++bug)\n\t\tif (bugaddr == bug_addr(bug))\n\t\t\tgoto out;\n\n... which can lead to a kenrel panic due to an unhandled bug.\n\nThis can be demonstrated with the following module:\n\n\tstatic int __init buginit(void)\n\t{\n\t\tWARN(1, \"hello\\n\");\n\t\treturn 0;\n\t}\n\n\tstatic void __exit bugexit(void)\n\t{\n\t}\n\n\tmodule_init(buginit);\n\tmodule_exit(bugexit);\n\tMODULE_LICENSE(\"GPL\");\n\n... which will trigger a kernel panic when loaded:\n\n\t------------[ cut here ]------------\n\thello\n\tUnexpected kernel BRK exception at EL1\n\tInternal error: BRK handler: 00000000f2000800 [#1] PREEMPT SMP\n\tModules linked in: hello(O+)\n\tCPU: 0 PID: 50 Comm: insmod Tainted: G           O       6.9.1 #8\n\tHardware name: linux,dummy-virt (DT)\n\tpstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n\tpc : buginit+0x18/0x1000 [hello]\n\tlr : buginit+0x18/0x1000 [hello]\n\tsp : ffff800080533ae0\n\tx29: ffff800080533ae0 x28: 0000000000000000 x27: 0000000000000000\n\tx26: ffffaba8c4e70510 x25: ffff800080533c30 x24: ffffaba8c4a28a58\n\tx23: 0000000000000000 x22: 0000000000000000 x21: ffff3947c0eab3c0\n\tx20: ffffaba8c4e3f000 x19: ffffaba846464000 x18: 0000000000000006\n\tx17: 0000000000000000 x16: ffffaba8c2492834 x15: 0720072007200720\n\tx14: 0720072007200720 x13: ffffaba8c49b27c8 x12: 0000000000000312\n\tx11: 0000000000000106 x10: ffffaba8c4a0a7c8 x9 : ffffaba8c49b27c8\n\tx8 : 00000000ffffefff x7 : ffffaba8c4a0a7c8 x6 : 80000000fffff000\n\tx5 : 0000000000000107 x4 : 0000000000000000 x3 : 0000000000000000\n\tx2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff3947c0eab3c0\n\tCall trace:\n\t buginit+0x18/0x1000 [hello]\n\t do_one_initcall+0x80/0x1c8\n\t do_init_module+0x60/0x218\n\t load_module+0x1ba4/0
            }
        ]
    },
    "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": "9fb7410f955f",
                                            "version_value": "f221bd58db0f"
                                        },
                                        {
                                            "version_value": "not down converted",
                                            "x_cve_json_5_version_data": {
                                                "versions": [
                                                    {
                                                        "version": "4.3",
                                                        "status": "affected"
                                                    },
                                                    {
                                                        "version": "0",
                                                        "lessThan": "4.3",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "4.19.316",
                                                        "lessThanOrEqual": "4.19.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "5.4.278",
                                                        "lessThanOrEqual": "5.4.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "5.10.219",
                                                        "lessThanOrEqual": "5.10.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "5.15.161",
                                                        "lessThanOrEqual": "5.15.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.1.93",
                                                        "lessThanOrEqual": "6.1.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.6.33",
                                                        "lessThanOrEqual": "6.6.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.9.4",
                                                        "lessThanOrEqual": "6.9.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.10",
                                                        "lessThanOrEqual": "*",
                                                        "status": "unaffected",
                                                        "versionType": "original_commit_for_fix"
                                                    }
                                                ],
                                                "defaultStatus": "affected"
                                            }
                                        }
                                    ]
                                }
                            }
                        ]
                    }
                }
            ]
        }
    },
    "references": {
        "reference_data": [
            {
                "url": "https://git.kernel.org/stable/c/f221bd58db0f6ca087ac0392284f6bce21f4f8ea",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/f221bd58db0f6ca087ac0392284f6bce21f4f8ea"
            },
            {
                "url": "https://git.kernel.org/stable/c/22469a0335a1a1a690349b58bcb55822457df81e",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/22469a0335a1a1a690349b58bcb55822457df81e"
            },
            {
                "url": "https://git.kernel.org/stable/c/461a760d578b2b2c2faac3040b6b7c77baf128f8",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/461a760d578b2b2c2faac3040b6b7c77baf128f8"
            },
            {
                "url": "https://git.kernel.org/stable/c/c1929c041a262a4a27265db8dce3619c92aa678c",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/c1929c041a262a4a27265db8dce3619c92aa678c"
            },
            {
                "url": "https://git.kernel.org/stable/c/3fd487ffaa697ddb05af78a75aaaddabe71c52b0",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/3fd487ffaa697ddb05af78a75aaaddabe71c52b0"
            },
            {
                "url": "https://git.kernel.org/stable/c/9f2ad88f9b349554f64e4037ec185c84d7dd9c7d",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/9f2ad88f9b349554f64e4037ec185c84d7dd9c7d"
            },
            {
                "url": "https://git.kernel.org/stable/c/c27a2f7668e215c1ebbccd96fab27a220a93f1f7",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/c27a2f7668e215c1ebbccd96fab27a220a93f1f7"
            },
            {
                "url": "https://git.kernel.org/stable/c/ffbf4fb9b5c12ff878a10ea17997147ea4ebea6f",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/ffbf4fb9b5c12ff878a10ea17997147ea4ebea6f"
            }
        ]
    },
    "generator": {
        "engine": "bippy-9e1c9544281a"
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