{
    "data_version": "4.0",
    "data_type": "CVE",
    "data_format": "MITRE",
    "CVE_data_meta": {
        "ID": "CVE-2024-56693",
        "ASSIGNER": "cve@kernel.org",
        "STATE": "PUBLIC"
    },
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbrd: defer automatic disk creation until module initialization succeeds\n\nMy colleague Wupeng found the following problems during fault injection:\n\nBUG: unable to handle page fault for address: fffffbfff809d073\nPGD 6e648067 P4D 123ec8067 PUD 123ec4067 PMD 100e38067 PTE 0\nOops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI\nCPU: 5 UID: 0 PID: 755 Comm: modprobe Not tainted 6.12.0-rc3+ #17\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nRIP: 0010:__asan_load8+0x4c/0xa0\n...\nCall Trace:\n <TASK>\n blkdev_put_whole+0x41/0x70\n bdev_release+0x1a3/0x250\n blkdev_release+0x11/0x20\n __fput+0x1d7/0x4a0\n task_work_run+0xfc/0x180\n syscall_exit_to_user_mode+0x1de/0x1f0\n do_syscall_64+0x6b/0x170\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nloop_init() is calling loop_add() after __register_blkdev() succeeds and\nis ignoring disk_add() failure from loop_add(), for loop_add() failure\nis not fatal and successfully created disks are already visible to\nbdev_open().\n\nbrd_init() is currently calling brd_alloc() before __register_blkdev()\nsucceeds and is releasing successfully created disks when brd_init()\nreturns an error. This can cause UAF for the latter two case:\n\ncase 1:\n    T1:\nmodprobe brd\n  brd_init\n    brd_alloc(0) // success\n      add_disk\n        disk_scan_partitions\n          bdev_file_open_by_dev // alloc file\n          fput // won't free until back to userspace\n    brd_alloc(1) // failed since mem alloc error inject\n  // error path for modprobe will release code segment\n  // back to userspace\n  __fput\n    blkdev_release\n      bdev_release\n        blkdev_put_whole\n          bdev->bd_disk->fops->release // fops is freed now, UAF!\n\ncase 2:\n    T1:                            T2:\nmodprobe brd\n  brd_init\n    brd_alloc(0) // success\n                                   open(/dev/ram0)\n    brd_alloc(1) // fail\n  // error path for modprobe\n\n                                   close(/dev/ram0)\n                                   ...\n                                   /* UAF! */\n                                   bdev->bd_disk->fops->release\n\nFix this problem by following what loop_init() does. Besides,\nreintroduce brd_devices_mutex to help serialize modifications to\nbrd_list."
            }
        ]
    },
    "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": "7f9b348cb5e94259acdcbafbcaed55d3bb515304",
                                            "version_value": "41219c147df8bbd6591f59af5d695fb6c9a1cbff"
                                        },
                                        {
                                            "version_value": "not down converted",
                                            "x_cve_json_5_version_data": {
                                                "versions": [
                                                    {
                                                        "version": "5.14",
                                                        "status": "affected"
                                                    },
                                                    {
                                                        "version": "0",
                                                        "lessThan": "5.14",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "5.15.174",
                                                        "lessThanOrEqual": "5.15.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.1.120",
                                                        "lessThanOrEqual": "6.1.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.6.64",
                                                        "lessThanOrEqual": "6.6.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.11.11",
                                                        "lessThanOrEqual": "6.11.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.12.2",
                                                        "lessThanOrEqual": "6.12.*",
                                                        "status": "unaffected",
                                                        "versionType": "semver"
                                                    },
                                                    {
                                                        "version": "6.13-rc1",
                                                        "lessThanOrEqual": "*",
                                                        "status": "unaffected",
                                                        "versionType": "original_commit_for_fix"
                                                    }
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                                                "defaultStatus": "affected"
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                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/259bf925583ec9e3781df778cadf00594095090d"
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                "name": "https://git.kernel.org/stable/c/410896624db639500f24f46478b4bfa05c76bf56"
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                "name": "https://git.kernel.org/stable/c/c0c2744cd2939ec5999c51dbaf2af16886548b7b"
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                "url": "https://git.kernel.org/stable/c/63dfd728b30f79495dacc886127695a379805152",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/63dfd728b30f79495dacc886127695a379805152"
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                "url": "https://git.kernel.org/stable/c/826cc42adf44930a633d11a5993676d85ddb0842",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/826cc42adf44930a633d11a5993676d85ddb0842"
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