GHSA-XV6R-2M8V-F893
Vulnerability from github – Published: 2024-03-15 21:30 – Updated: 2025-01-07 18:30In the Linux kernel, the following vulnerability has been resolved:
ext4: fix memory leak in ext4_fill_super
Buffer head references must be released before calling kill_bdev(); otherwise the buffer head (and its page referenced by b_data) will not be freed by kill_bdev, and subsequently that bh will be leaked.
If blocksizes differ, sb_set_blocksize() will kill current buffers and page cache by using kill_bdev(). And then super block will be reread again but using correct blocksize this time. sb_set_blocksize() didn't fully free superblock page and buffer head, and being busy, they were not freed and instead leaked.
This can easily be reproduced by calling an infinite loop of:
systemctl start .mount, and systemctl stop .mount
... since systemd creates a cgroup for each slice which it mounts, and the bh leak get amplified by a dying memory cgroup that also never gets freed, and memory consumption is much more easily noticed.
{
"affected": [],
"aliases": [
"CVE-2021-47119"
],
"database_specific": {
"cwe_ids": [
"CWE-401"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-15T21:15:07Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix memory leak in ext4_fill_super\n\nBuffer head references must be released before calling kill_bdev();\notherwise the buffer head (and its page referenced by b_data) will not\nbe freed by kill_bdev, and subsequently that bh will be leaked.\n\nIf blocksizes differ, sb_set_blocksize() will kill current buffers and\npage cache by using kill_bdev(). And then super block will be reread\nagain but using correct blocksize this time. sb_set_blocksize() didn\u0027t\nfully free superblock page and buffer head, and being busy, they were\nnot freed and instead leaked.\n\nThis can easily be reproduced by calling an infinite loop of:\n\n systemctl start \u003cext4_on_lvm\u003e.mount, and\n systemctl stop \u003cext4_on_lvm\u003e.mount\n\n... since systemd creates a cgroup for each slice which it mounts, and\nthe bh leak get amplified by a dying memory cgroup that also never\ngets freed, and memory consumption is much more easily noticed.",
"id": "GHSA-xv6r-2m8v-f893",
"modified": "2025-01-07T18:30:38Z",
"published": "2024-03-15T21:30:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47119"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/afd09b617db3786b6ef3dc43e28fe728cfea84df"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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