{
    "data_version": "4.0",
    "data_type": "CVE",
    "data_format": "MITRE",
    "CVE_data_meta": {
        "ID": "CVE-2021-47488",
        "ASSIGNER": "cve@kernel.org",
        "STATE": "PUBLIC"
    },
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup: Fix memory leak caused by missing cgroup_bpf_offline\n\nWhen enabling CONFIG_CGROUP_BPF, kmemleak can be observed by running\nthe command as below:\n\n    $mount -t cgroup -o none,name=foo cgroup cgroup/\n    $umount cgroup/\n\nunreferenced object 0xc3585c40 (size 64):\n  comm \"mount\", pid 425, jiffies 4294959825 (age 31.990s)\n  hex dump (first 32 bytes):\n    01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00  ......(.........\n    00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00  ........lC......\n  backtrace:\n    [<e95a2f9e>] cgroup_bpf_inherit+0x44/0x24c\n    [<1f03679c>] cgroup_setup_root+0x174/0x37c\n    [<ed4b0ac5>] cgroup1_get_tree+0x2c0/0x4a0\n    [<f85b12fd>] vfs_get_tree+0x24/0x108\n    [<f55aec5c>] path_mount+0x384/0x988\n    [<e2d5e9cd>] do_mount+0x64/0x9c\n    [<208c9cfe>] sys_mount+0xfc/0x1f4\n    [<06dd06e0>] ret_fast_syscall+0x0/0x48\n    [<a8308cb3>] 0xbeb4daa8\n\nThis is because that since the commit 2b0d3d3e4fcf (\"percpu_ref: reduce\nmemory footprint of percpu_ref in fast path\") root_cgrp->bpf.refcnt.data\nis allocated by the function percpu_ref_init in cgroup_bpf_inherit which\nis called by cgroup_setup_root when mounting, but not freed along with\nroot_cgrp when umounting. Adding cgroup_bpf_offline which calls\npercpu_ref_kill to cgroup_kill_sb can free root_cgrp->bpf.refcnt.data in\numount path.\n\nThis patch also fixes the commit 4bfc0bb2c60e (\"bpf: decouple the lifetime\nof cgroup_bpf from cgroup itself\"). A cgroup_bpf_offline is needed to do a\ncleanup that frees the resources which are allocated by cgroup_bpf_inherit\nin cgroup_setup_root.\n\nAnd inside cgroup_bpf_offline, cgroup_get() is at the beginning and\ncgroup_put is at the end of cgroup_bpf_release which is called by\ncgroup_bpf_offline. So cgroup_bpf_offline can keep the balance of\ncgroup's refcount."
            }
        ]
    },
    "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": "4bfc0bb2c60e",
                                            "version_value": "01599bf7cc2b"
                                        },
                                        {
                                            "version_value": "not down converted",
                                            "x_cve_json_5_version_data": {
                                                "versions": [
                                                    {
                                                        "version": "5.3",
                                                        "status": "affected"
                                                    },
                                                    {
                                                        "version": "0",
                                                        "lessThan": "5.3",
                                                        "status": "unaffected",
                                                        "versionType": "custom"
                                                    },
                                                    {
                                                        "version": "5.10.77",
                                                        "lessThanOrEqual": "5.10.*",
                                                        "status": "unaffected",
                                                        "versionType": "custom"
                                                    },
                                                    {
                                                        "version": "5.14.16",
                                                        "lessThanOrEqual": "5.14.*",
                                                        "status": "unaffected",
                                                        "versionType": "custom"
                                                    },
                                                    {
                                                        "version": "5.15",
                                                        "lessThanOrEqual": "*",
                                                        "status": "unaffected",
                                                        "versionType": "original_commit_for_fix"
                                                    }
                                                ],
                                                "defaultStatus": "affected"
                                            }
                                        }
                                    ]
                                }
                            }
                        ]
                    }
                }
            ]
        }
    },
    "references": {
        "reference_data": [
            {
                "url": "https://git.kernel.org/stable/c/01599bf7cc2b49c3d2be886cb438647dc25446ed",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/01599bf7cc2b49c3d2be886cb438647dc25446ed"
            },
            {
                "url": "https://git.kernel.org/stable/c/b529f88d93884cf8ccafda793ee3d27b82fa578d",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/b529f88d93884cf8ccafda793ee3d27b82fa578d"
            },
            {
                "url": "https://git.kernel.org/stable/c/04f8ef5643bcd8bcde25dfdebef998aea480b2ba",
                "refsource": "MISC",
                "name": "https://git.kernel.org/stable/c/04f8ef5643bcd8bcde25dfdebef998aea480b2ba"
            }
        ]
    },
    "generator": {
        "engine": "bippy-a5840b7849dd"
    }
}