{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-99174",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-09-25T10:25:14.399Z",
        "datePublished": "2026-10-28T10:35:28.758Z",
        "dateUpdated": "2026-10-28T10:35:28.758Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-10-28T10:35:28.758Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: free the sbi after a grace period\n\next4_get_link() follows a symlink that keeps its target in a data block\nin rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).\nThat reads s_mount_state in the ASSERT() of ext4_getblk() and again in\next4_es_lookup_extent(), and the lookup bumps the extent status hit or\nmiss counter, all through sb->s_fs_info.\n\next4_put_super() destroys those counters, clears sb->s_fs_info and frees\nthe sbi without waiting for a grace period. A pathwalk that is still in\next4_get_link() when the last reference to the mount goes away then\ndereferences a NULL s_fs_info, the freed sbi or the destroyed percpu\ncounters.\n\nWith a pathwalk held up in ext4_get_link() while the last reference\ngoes away:\n\n  KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]\n  RIP: 0010:ext4_getblk+0xf0/0x640\n  Call Trace:\n   <TASK>\n   ext4_get_link+0x26c/0x410\n   pick_link+0xf96/0x1780\n   step_into_slowpath+0x9b8/0x1250\n   path_lookupat+0x484/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n   vfs_fstatat+0x4d/0x90\n   __do_sys_newfstatat+0xa0/0x100\n   do_syscall_64+0x10e/0x5e0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nSo far that has been hard to hit. umount(2) waits for a grace period in\nnamespace_unlock() before it drops the mount, so only a mount whose last\nreference goes away elsewhere, like the close of a file or a chdir out of\na lazily unmounted directory, can race a walker.\n\nKeep sb->s_fs_info and free the sbi together with the extent status\ncounters after a grace period. Split the counters out of\next4_es_unregister_shrinker() for that. The shrinker still gets wasted\nin ext4_put_super(), the counters go with the sbi."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/ext4/ext4.h",
                        "fs/ext4/extents-test.c",
                        "fs/ext4/extents.c",
                        "fs/ext4/extents_status.c",
                        "fs/ext4/extents_status.h",
                        "fs/ext4/super.c"
                    ],
                    "versions": [
                        {
                            "version": "6493792d3299b3e33f887ef8a150099d271faf9c",
                            "lessThan": "80d5db1686b05fad6f384be017714297d828a714",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "6493792d3299b3e33f887ef8a150099d271faf9c",
                            "lessThan": "87d29b8b849738d52fe820d495fa0aa2d5a1ec82",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "6493792d3299b3e33f887ef8a150099d271faf9c",
                            "lessThan": "c17b44266a1f9fcb49b894d4611d1254bf1aa313",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/ext4/ext4.h",
                        "fs/ext4/extents-test.c",
                        "fs/ext4/extents.c",
                        "fs/ext4/extents_status.c",
                        "fs/ext4/extents_status.h",
                        "fs/ext4/super.c"
                    ],
                    "versions": [
                        {
                            "version": "5.19",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "5.19",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.59",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.13",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "5.19",
                                    "versionEndExcluding": "6.18.59"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "5.19",
                                    "versionEndExcluding": "7.2.13"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "5.19",
                                    "versionEndExcluding": "7.3"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/80d5db1686b05fad6f384be017714297d828a714"
                },
                {
                    "url": "https://git.kernel.org/stable/c/87d29b8b849738d52fe820d495fa0aa2d5a1ec82"
                },
                {
                    "url": "https://git.kernel.org/stable/c/c17b44266a1f9fcb49b894d4611d1254bf1aa313"
                }
            ],
            "title": "ext4: free the sbi after a grace period",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}