{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38710", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:24.033Z", "datePublished": "2025-09-04T15:33:00.629Z", "dateUpdated": "2026-08-05T12:04:10.498Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:04:10.498Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: Validate i_depth for exhash directories\n\nA fuzzer test introduced corruption that ends up with a depth of 0 in\ndir_e_read(), causing an undefined shift by 32 at:\n\n index = hash >> (32 - dip->i_depth);\n\nAs calculated in an open-coded way in dir_make_exhash(), the minimum\ndepth for an exhash directory is ilog2(sdp->sd_hash_ptrs) and 0 is\ninvalid as sdp->sd_hash_ptrs is fixed as sdp->bsize / 16 at mount time.\n\nSo we can avoid the undefined behaviour by checking for depth values\nlower than the minimum in gfs2_dinode_in(). Values greater than the\nmaximum are already being checked for there.\n\nAlso switch the calculation in dir_make_exhash() to use ilog2() to\nclarify how the depth is calculated.\n\nTested with the syzkaller repro.c and xfstests '-g quick'." } ], "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 corrupt `di_depth` reaches the kernel only by mounting an attacker-crafted GFS2 volume (loop device, removable media, or a shared cluster LUN), after which the flaw is triggered by ordinary local syscalls (`open`/`stat`/`getdents`) on that mount. GFS2 is a shared-disk filesystem with no network-protocol front end, so there is no remote parser path.\nAC:L - The condition is a deterministic inconsistency the attacker fully authors on disk (`GFS2_DIF_EXHASH` set, `di_depth = 0`, `di_size = 8`), and the out-of-bounds index is chosen exactly by picking a filename whose CRC32 hash equals the desired 32-bit offset. No race, no timing window, and no memory-layout condition outside the attacker's control.\nPR:L - The bare `mount(2)` needs CAP_SYS_ADMIN (gfs2 lacks FS_USERNS_MOUNT), but in the most severe reasonable deployment an unprivileged user gets the crafted volume mounted through udisks2 loop-setup/removable-media automount or `user`/autofs fstab delegation, and the trigger itself — a path lookup or `getdents` on the bad directory — requires only basic unprivileged access to the mount.\nUI:N - In the automount/loop-setup scenario the attacker presents the media and initiates the mount themselves, and at the point of exploitation the out-of-bounds read fires from the attacker's own `open()`/`stat()` call. No second user has to take any action.\nS:U - The out-of-bounds access, the wild block read, and the hang all occur in GFS2 code inside the kernel's own security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - `get_leaf_nr()` reads a 64-bit word at `hash + 8*index` where `index` is a fully attacker-chosen 32-bit value and the allocation is 8 bytes — an unbounded slab out-of-bounds read reaching up to 32 GiB past the object, far beyond a \"few bytes\" bounded read. The value read becomes a block number handed to `gfs2_meta_read()`, giving an observable oracle on kernel heap contents through lookup success/failure and the resulting I/O.\nI:H - Out-of-bounds heap data is promoted to a filesystem block number, and `dir_new_leaf()`/`gfs2_dir_add()` then write directory metadata (`oleaf->lf_next`, `be16_add_cpu(&leaf->lf_entries, 1)`) into the buffer for that attacker-influenced block, so kernel-side data read past the object's bounds steers subsequent metadata writes to arbitrary blocks of the device — including a shared cluster LUN.\nA:H - A read up to 32 GiB past an 8-byte slab object will typically strike unmapped memory and produce a kernel oops/page fault (KASAN reports it as slab-out-of-bounds), and `dir_e_read()` independently spins forever because `len` truncates to 0 so `index` never advances, wedging `getdents()` while holding the directory glock and stalling the mount — a full panic on `panic_on_oops` configurations, repeatable on demand." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/gfs2/dir.c", "fs/gfs2/glops.c" ], "versions": [ { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "076e992752e4b24178918f748d75597c80a408d2", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "366183911b153e9b8cf758e1414e1154d7569337", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "112bb60cd0e254a369e95aa9941a694ffeca089f", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "cddea0c721106ea480371412d8de21705eb27376", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "53a0249d68a210c16e961b83adfa82f94ee0a53d", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "b5f46951e62377b6e406fadc18bc3c5bdf1632a7", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "9680c58675b82348ab84d387e4fa727f7587e1a0", "status": "affected", "versionType": "git" }, { "version": "9a0045088d888c9c539c8c626a366cb52c0fbdab", "lessThan": "557c024ca7250bb65ae60f16c02074106c2f197b", "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/gfs2/dir.c", "fs/gfs2/glops.c" ], "versions": [ { "version": "2.6.26", "status": "affected" }, { "version": "0", "lessThan": "2.6.26", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.258", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.209", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.175", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.134", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.43", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15.11", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.2", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "2.6.26", "versionEndExcluding": "5.10.258" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "5.15.209" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.1.175" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.6.134" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.12.43" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.15.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.16.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/076e992752e4b24178918f748d75597c80a408d2" }, { "url": "https://git.kernel.org/stable/c/366183911b153e9b8cf758e1414e1154d7569337" }, { "url": "https://git.kernel.org/stable/c/112bb60cd0e254a369e95aa9941a694ffeca089f" }, { "url": "https://git.kernel.org/stable/c/cddea0c721106ea480371412d8de21705eb27376" }, { "url": "https://git.kernel.org/stable/c/53a0249d68a210c16e961b83adfa82f94ee0a53d" }, { "url": "https://git.kernel.org/stable/c/b5f46951e62377b6e406fadc18bc3c5bdf1632a7" }, { "url": "https://git.kernel.org/stable/c/9680c58675b82348ab84d387e4fa727f7587e1a0" }, { "url": "https://git.kernel.org/stable/c/557c024ca7250bb65ae60f16c02074106c2f197b" } ], "title": "gfs2: Validate i_depth for exhash directories", "x_generator": { "engine": "bippy-1.2.0" } } } }