ghsa-hc99-rgj6-64qj
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
bcache: avoid journal no-space deadlock by reserving 1 journal bucket
The journal no-space deadlock was reported time to time. Such deadlock can happen in the following situation.
When all journal buckets are fully filled by active jset with heavy write I/O load, the cache set registration (after a reboot) will load all active jsets and inserting them into the btree again (which is called journal replay). If a journaled bkey is inserted into a btree node and results btree node split, new journal request might be triggered. For example, the btree grows one more level after the node split, then the root node record in cache device super block will be upgrade by bch_journal_meta() from bch_btree_set_root(). But there is no space in journal buckets, the journal replay has to wait for new journal bucket to be reclaimed after at least one journal bucket replayed. This is one example that how the journal no-space deadlock happens.
The solution to avoid the deadlock is to reserve 1 journal bucket in run time, and only permit the reserved journal bucket to be used during cache set registration procedure for things like journal replay. Then the journal space will never be fully filled, there is no chance for journal no-space deadlock to happen anymore.
This patch adds a new member "bool do_reserve" in struct journal, it is inititalized to 0 (false) when struct journal is allocated, and set to 1 (true) by bch_journal_space_reserve() when all initialization done in run_cache_set(). In the run time when journal_reclaim() tries to allocate a new journal bucket, free_journal_buckets() is called to check whether there are enough free journal buckets to use. If there is only 1 free journal bucket and journal->do_reserve is 1 (true), the last bucket is reserved and free_journal_buckets() will return 0 to indicate no free journal bucket. Then journal_reclaim() will give up, and try next time to see whetheer there is free journal bucket to allocate. By this method, there is always 1 jouranl bucket reserved in run time.
During the cache set registration, journal->do_reserve is 0 (false), so the reserved journal bucket can be used to avoid the no-space deadlock.
{
"affected": [],
"aliases": [
"CVE-2022-49327"
],
"database_specific": {
"cwe_ids": [
"CWE-667"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-26T07:01:09Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbcache: avoid journal no-space deadlock by reserving 1 journal bucket\n\nThe journal no-space deadlock was reported time to time. Such deadlock\ncan happen in the following situation.\n\nWhen all journal buckets are fully filled by active jset with heavy\nwrite I/O load, the cache set registration (after a reboot) will load\nall active jsets and inserting them into the btree again (which is\ncalled journal replay). If a journaled bkey is inserted into a btree\nnode and results btree node split, new journal request might be\ntriggered. For example, the btree grows one more level after the node\nsplit, then the root node record in cache device super block will be\nupgrade by bch_journal_meta() from bch_btree_set_root(). But there is no\nspace in journal buckets, the journal replay has to wait for new journal\nbucket to be reclaimed after at least one journal bucket replayed. This\nis one example that how the journal no-space deadlock happens.\n\nThe solution to avoid the deadlock is to reserve 1 journal bucket in\nrun time, and only permit the reserved journal bucket to be used during\ncache set registration procedure for things like journal replay. Then\nthe journal space will never be fully filled, there is no chance for\njournal no-space deadlock to happen anymore.\n\nThis patch adds a new member \"bool do_reserve\" in struct journal, it is\ninititalized to 0 (false) when struct journal is allocated, and set to\n1 (true) by bch_journal_space_reserve() when all initialization done in\nrun_cache_set(). In the run time when journal_reclaim() tries to\nallocate a new journal bucket, free_journal_buckets() is called to check\nwhether there are enough free journal buckets to use. If there is only\n1 free journal bucket and journal-\u003edo_reserve is 1 (true), the last\nbucket is reserved and free_journal_buckets() will return 0 to indicate\nno free journal bucket. Then journal_reclaim() will give up, and try\nnext time to see whetheer there is free journal bucket to allocate. By\nthis method, there is always 1 jouranl bucket reserved in run time.\n\nDuring the cache set registration, journal-\u003edo_reserve is 0 (false), so\nthe reserved journal bucket can be used to avoid the no-space deadlock.",
"id": "GHSA-hc99-rgj6-64qj",
"modified": "2025-03-14T00:30:51Z",
"published": "2025-03-14T00:30:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49327"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1dda32aed6f62c163f38ff947ef5b3360e329159"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/32feee36c30ea06e38ccb8ae6e5c44c6eec790a6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5607652823ac65e2c6885e73bd46d5a4f9a20363"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/59afd4f287900c8187e968a4153ed35e6b48efce"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6332ea3e35efa12dc08f0cbf5faea5e6e8eb0497"
}
],
"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"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
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