CVE-2026-74307
In the Linux kernel, the following vulnerability has been resolved:
ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT
Reject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not belong to the same superblock as the original file. Currently, this validation is performed inside ext4_move_extents() by mext_check_validity(), but only after lock_two_nondirectories() has already acquired the inode locks. When the donor fd refers to a file on a different filesystem (e.g., overlayfs), this late validation creates a circular lock dependency:
With a concurrent freeze operation holding sb_writers write side, this forms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits for CPU1's sb_writers reader to exit, CPU1 waits for CPU0's inode lock.
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Since EXT4_IOC_MOVE_EXT exchanges physical extents between two files, it fundamentally requires both files to reside on the same ext4 filesystem. Moving the superblock check before any lock acquisition is both semantically correct and eliminates the circular dependency by ensuring that cross-filesystem donor fds are rejected before sb_writers or inode locks are taken.
Detalles técnicos trazas, registros y código del informe original
CPU0 (overlayfs write) CPU1 (ext4 ioctl)
---- ----
inode_lock(ovl_inode)
mnt_want_write_file(filp)
sb_start_write(ext4_sb) [sb_writers]
backing_file_write_iter()
vfs_iter_write(real_file)
file_start_write(real_file)
sb_start_write(ext4_sb) [blocked by freeze]
lock_two_nondirectories()
inode_lock(ovl_inode) [blocked]CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-74307",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a",
"lessThan": "74796e886ca39fcb0d3fd36ea6a39c62784ab6fb",
"versionType": "git"
},
{
"status": "affected",
"version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a",
"lessThan": "fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c",
"versionType": "git"
},
{
"status": "affected",
"version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a",
"lessThan": "c143957520c6c9b5cd72e0de8b52b814f0c576fe",
"versionType": "git"
}
],
"programFiles": [
"fs/ext4/ioctl.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.18"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.18",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/ext4/ioctl.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-15T06:22:30.500",
"references": [
{
"url": "https://git.kernel.org/stable/c/74796e886ca39fcb0d3fd36ea6a39c62784ab6fb",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c143957520c6c9b5cd72e0de8b52b814f0c576fe",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: validate donor file superblock early in EXT4_IOC_MOVE_EXT\n\nReject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not\nbelong to the same superblock as the original file. Currently, this\nvalidation is performed inside ext4_move_extents() by\nmext_check_validity(), but only after lock_two_nondirectories() has\nalready acquired the inode locks. When the donor fd refers to a file\non a different filesystem (e.g., overlayfs), this late validation\ncreates a circular lock dependency:\n\n CPU0 (overlayfs write) CPU1 (ext4 ioctl)\n ---- ----\n inode_lock(ovl_inode)\n mnt_want_write_file(filp)\n sb_start_write(ext4_sb) [sb_writers]\n backing_file_write_iter()\n vfs_iter_write(real_file)\n file_start_write(real_file)\n sb_start_write(ext4_sb) [blocked by freeze]\n lock_two_nondirectories()\n inode_lock(ovl_inode) [blocked]\n\nWith a concurrent freeze operation holding sb_writers write side, this\nforms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits\nfor CPU1's sb_writers reader to exit, CPU1 waits for CPU0's inode lock.\n\nSince EXT4_IOC_MOVE_EXT exchanges physical extents between two files,\nit fundamentally requires both files to reside on the same ext4\nfilesystem. Moving the superblock check before any lock acquisition\nis both semantically correct and eliminates the circular dependency\nby ensuring that cross-filesystem donor fds are rejected before\nsb_writers or inode locks are taken."
}
],
"lastModified": "2026-08-17T06:19:24.907",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}