GHSA-R2MM-CWFF-HC2Q
Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31In the Linux kernel, the following vulnerability has been resolved:
io_uring/cmd: fix iovec leak when the async cmd is not recycled
An io_async_cmd carries an iovec array in ->vec.iovec, allocated when the vec has to grow and kept across recycling through ctx->cmd_cache. On two paths nothing frees it and io_clean_op()'s kfree(req->async_data) drops the io_async_cmd without it.
io_req_uring_cleanup() clears the async data flags only when io_alloc_cache_put() succeeds, and the cache holds IO_ALLOC_CACHE_MAX == 128 entries, so once it is full the put fails and the vec is left behind. An NVMe passthrough workload gets there without doing anything unusual: nvme_uring_cmd_io() returns -EIOCBQUEUED, so the io_async_cmd stays attached for the lifetime of the command and the live object count tracks the queue depth. Above 128 the puts start failing.
->cleanup is the last chance to free an inherited vec, since io_req_uring_cleanup() returns early for an io-wq issued command and is not called at all for one completed without ever being issued. But io_clean_op() calls ->cleanup only if REQ_F_NEED_CLEANUP is set, and for uring_cmd that happens only where the vec has to grow, so a command reusing a large enough cached vec never sets it. io_rw_alloc_async() and io_msg_alloc_async() flag an inherited vec for exactly this reason; io_uring_cmd_prep() does not.
Flag an inherited vec in io_uring_cmd_prep(), and free the vec when the cache put fails, as io_req_rw_cleanup() does.
The leak is invisible under KASAN, where io_alloc_cache_vec_kasan() frees the vec unconditionally.
{
"affected": [],
"aliases": [
"CVE-2026-80811"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-04T16:18:08Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/cmd: fix iovec leak when the async cmd is not recycled\n\nAn io_async_cmd carries an iovec array in -\u003evec.iovec, allocated when the\nvec has to grow and kept across recycling through ctx-\u003ecmd_cache. On two\npaths nothing frees it and io_clean_op()\u0027s kfree(req-\u003easync_data) drops\nthe io_async_cmd without it.\n\nio_req_uring_cleanup() clears the async data flags only when\nio_alloc_cache_put() succeeds, and the cache holds IO_ALLOC_CACHE_MAX ==\n128 entries, so once it is full the put fails and the vec is left behind.\nAn NVMe passthrough workload gets there without doing anything unusual:\nnvme_uring_cmd_io() returns -EIOCBQUEUED, so the io_async_cmd stays\nattached for the lifetime of the command and the live object count tracks\nthe queue depth. Above 128 the puts start failing.\n\n-\u003ecleanup is the last chance to free an inherited vec, since\nio_req_uring_cleanup() returns early for an io-wq issued command and is\nnot called at all for one completed without ever being issued. But\nio_clean_op() calls -\u003ecleanup only if REQ_F_NEED_CLEANUP is set, and for\nuring_cmd that happens only where the vec has to grow, so a command\nreusing a large enough cached vec never sets it. io_rw_alloc_async() and\nio_msg_alloc_async() flag an inherited vec for exactly this reason;\nio_uring_cmd_prep() does not.\n\nFlag an inherited vec in io_uring_cmd_prep(), and free the vec when the\ncache put fails, as io_req_rw_cleanup() does.\n\nThe leak is invisible under KASAN, where io_alloc_cache_vec_kasan() frees\nthe vec unconditionally.",
"id": "GHSA-r2mm-cwff-hc2q",
"modified": "2026-09-04T18:31:27Z",
"published": "2026-09-04T18:31:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80811"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7068d3587a64a24943a7c9e232976da2c9e0e303"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b290de4d16d75b6c1ef42025b47f5d94eb1ec09f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b6a768aa975b9ca81b92f028bdd975d1f8237894"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bb34ae5da3365699d53a756f4c96b6ea9f8ba0c1"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.