{ "dataType": "CVE_RECORD", "cveMetadata": { "cveId": "CVE-2024-26704", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-19T14:20:24.158Z", "datePublished": "2024-04-03T14:55:02.672Z", "dateUpdated": "2026-08-05T11:26:47.486Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:26:47.486Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix double-free of blocks due to wrong extents moved_len\n\nIn ext4_move_extents(), moved_len is only updated when all moves are\nsuccessfully executed, and only discards orig_inode and donor_inode\npreallocations when moved_len is not zero. When the loop fails to exit\nafter successfully moving some extents, moved_len is not updated and\nremains at 0, so it does not discard the preallocations.\n\nIf the moved extents overlap with the preallocated extents, the\noverlapped extents are freed twice in ext4_mb_release_inode_pa() and\next4_process_freed_data() (as described in commit 94d7c16cbbbd (\"ext4:\nFix double-free of blocks with EXT4_IOC_MOVE_EXT\")), and bb_free is\nincremented twice. Hence when trim is executed, a zero-division bug is\ntriggered in mb_update_avg_fragment_size() because bb_free is not zero\nand bb_fragments is zero.\n\nTherefore, update move_len after each extent move to avoid the issue." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only through the EXT4_IOC_MOVE_EXT ioctl on a local ext4 filesystem, requiring the attacker to hold open file descriptors on the machine. There is no remote or adjacent-network path to fs/ext4/move_extent.c.\nAC:L - The early-exit path is fully attacker-controlled — a sparse orig file whose first extent swaps successfully and whose next lookup returns EXT_MAX_BLOCKS deterministically yields -ENODATA with moved_len==0, leaving the preallocations undiscarded. No race, no memory-layout dependency, and mb_optimize_scan (needed for the divide error) is on by default for any ext4 volume of ~2 GiB or larger.\nPR:L - EXT4_IOC_MOVE_EXT has no capable() or inode_owner_or_capable() check — it only requires both files be open O_RDWR, so any unprivileged local user (including one confined to a container) can invoke it on files they own in /tmp or /home.\nUI:N - The attacker performs every step — creating the two files, shaping the extent layout, seeding the preallocations, and issuing the ioctl. No victim action is needed, since the target ext4 filesystem is already mounted on any normal system.\nS:U - The double free, bitmap corruption, and divide-error oops all occur within the kernel's own security authority on the same host. No hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The double free returns blocks that are still referenced by a live inode to the free-space bitmap, so they can be reallocated into an attacker-controlled file, exposing another user's file contents through cross-file block aliasing. This is an unbounded read of arbitrary on-disk data belonging to other users.\nI:H - The same block aliasing lets the attacker overwrite data blocks still owned by another inode, and mb_free_blocks() additionally marks the group bitmap corrupt while inflating bb_free, leaving persistent allocator and on-disk metadata corruption. That is arbitrary modification of other users' file data and of filesystem metadata.\nA:H - The inconsistent bb_free/bb_fragments state causes a divide-by-zero oops in mb_update_avg_fragment_size() while ext4_lock_group() is held, so the group spinlock is orphaned and subsequent accesses deadlock. Even short of that, ext4_grp_locked_error() forces the filesystem read-only under the default errors=remount-ro, or panics the kernel under errors=panic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/move_extent.c" ], "versions": [ { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "b4fbb89d722cbb16beaaea234b7230faaaf68c71", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "afbcad9ae7d6d11608399188f03a837451b6b3a1", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "d033a555d9a1cf53dbf3301af7199cc4a4c8f537", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "afba9d11320dad5ce222ac8964caf64b7b4bedb1", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "185eab30486ba3e7bf8b9c2e049c79a06ffd2bc1", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "2883940b19c38d5884c8626483811acf4d7e148f", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "559ddacb90da1d8786dd8ec4fd76bbfa404eaef6", "status": "affected", "versionType": "git" }, { "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a", "lessThan": "55583e899a5357308274601364741a83e78d6ac4", "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/move_extent.c" ], "versions": [ { "version": "3.18", "status": "affected" }, { "version": "0", "lessThan": "3.18", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.307", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.269", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.210", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.149", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.79", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.18", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.7.6", "lessThanOrEqual": "6.7.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.8", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": 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"versionEndExcluding": "6.7.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18", "versionEndExcluding": "6.8" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/b4fbb89d722cbb16beaaea234b7230faaaf68c71" }, { "url": "https://git.kernel.org/stable/c/afbcad9ae7d6d11608399188f03a837451b6b3a1" }, { "url": "https://git.kernel.org/stable/c/d033a555d9a1cf53dbf3301af7199cc4a4c8f537" }, { "url": "https://git.kernel.org/stable/c/afba9d11320dad5ce222ac8964caf64b7b4bedb1" }, { "url": "https://git.kernel.org/stable/c/185eab30486ba3e7bf8b9c2e049c79a06ffd2bc1" }, { "url": "https://git.kernel.org/stable/c/2883940b19c38d5884c8626483811acf4d7e148f" }, { "url": "https://git.kernel.org/stable/c/559ddacb90da1d8786dd8ec4fd76bbfa404eaef6" }, { "url": "https://git.kernel.org/stable/c/55583e899a5357308274601364741a83e78d6ac4" } ], "title": "ext4: fix double-free of blocks due to wrong extents moved_len", "x_generator": { 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