GHSA-M9PV-2424-H7VV
Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-19 18:32In the Linux kernel, the following vulnerability has been resolved:
fscrypt: Avoid dynamic allocation in fscrypt_get_devices()
When a blk_crypto_key starts being used or is evicted, fs/crypto/ calls fscrypt_get_devices() to get the filesystem's list of block devices, then iterates over them and calls blk_crypto_config_supported(), blk_crypto_start_using_key(), or blk_crypto_evict_key() on each one.
Currently, the block device pointers are placed in a dynamically allocated array. This dynamic allocation is problematic because:
-
It can fail, especially at the fscrypt_destroy_inline_crypt_key() call site when it's invoked for inode eviction under direct reclaim.
-
fscrypt_destroy_inline_crypt_key() doesn't handle the failure. It just zeroizes and frees the blk_crypto_key without calling blk_crypto_evict_key(). That causes a use-after-free.
For now, let's fix this in the straightforward and easily-backportable way by switching to an on-stack array. Currently the fscrypt multi-device functionality is used only by f2fs, which has a hardcoded limit of 8 block devices. An on-stack array works fine for that.
(Of course, this solution won't scale up to large number of block devices. For that we'd need a different solution, like moving the block device iteration into the filesystem. Or in the case of btrfs, which will only support blk-crypto-fallback, we should make it just call blk-crypto-fallback directly, so the block devices won't be needed.)
{
"affected": [],
"aliases": [
"CVE-2026-68147"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-10T13:20:00Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfscrypt: Avoid dynamic allocation in fscrypt_get_devices()\n\nWhen a blk_crypto_key starts being used or is evicted, fs/crypto/ calls\nfscrypt_get_devices() to get the filesystem\u0027s list of block devices,\nthen iterates over them and calls blk_crypto_config_supported(),\nblk_crypto_start_using_key(), or blk_crypto_evict_key() on each one.\n\nCurrently, the block device pointers are placed in a dynamically\nallocated array. This dynamic allocation is problematic because:\n\n- It can fail, especially at the fscrypt_destroy_inline_crypt_key() call\n site when it\u0027s invoked for inode eviction under direct reclaim.\n\n- fscrypt_destroy_inline_crypt_key() doesn\u0027t handle the failure. It\n just zeroizes and frees the blk_crypto_key without calling\n blk_crypto_evict_key(). That causes a use-after-free.\n\nFor now, let\u0027s fix this in the straightforward and easily-backportable\nway by switching to an on-stack array. Currently the fscrypt\nmulti-device functionality is used only by f2fs, which has a hardcoded\nlimit of 8 block devices. An on-stack array works fine for that.\n\n(Of course, this solution won\u0027t scale up to large number of block\ndevices. For that we\u0027d need a different solution, like moving the block\ndevice iteration into the filesystem. Or in the case of btrfs, which\nwill only support blk-crypto-fallback, we should make it just call\nblk-crypto-fallback directly, so the block devices won\u0027t be needed.)",
"id": "GHSA-m9pv-2424-h7vv",
"modified": "2026-08-19T18:32:07Z",
"published": "2026-08-10T15:33:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68147"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4462ac3d90e897dda52ce4b6af2d526ddae835a8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6fe4e4b8259e1330945b5f3c9476e08473b8e0e8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/81ea8e8221853950c47dac7164f27c63a96f8f86"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/97a688563be71ec6fefc071aff69a66c69dbe244"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bab016bb80d74a9d1f7d4121a7fc1cb529b470e0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bc2d630296e0e049210ec05ff08459a6893ae749"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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