GHSA-XQQX-XHMM-5H73
Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-09-21 15:31In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_fs: Fix Use-After-Free in AIO error path
In ffs_epfile_write_iter() and ffs_epfile_read_iter(), when ffs_epfile_io()
fails with an error other than -EIOCBQUEUED, the io_data structure (p) is
freed. However, for AIO operations, the kiocb cancel function was already
armed and kiocb->private was set to p.
If a concurrent cancel operation (such as sys_io_cancel()) executes after
ffs_epfile_io() fails but before the function frees p, a Use-After-Free
can occur when the cancellation handler accesses the freed pointer.
To securely fix this race condition, we must properly un-arm the
cancellation. Invoking kiocb->ki_complete() does exactly this by
acquiring ctx->ctx_lock and safely removing the kiocb from the active
sequence. In doing so, it ensures that a parallel io_cancel can no longer
discover the kiocb, effectively closing the race window.
We then return -EIOCBQUEUED to notify the VFS layer that the kiocb has been consumed and it should avoid attempting to complete the request again or triggering subsequent completion handlers.
{
"affected": [],
"aliases": [
"CVE-2026-90044"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-16T11:17:17Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_fs: Fix Use-After-Free in AIO error path\n\nIn ffs_epfile_write_iter() and ffs_epfile_read_iter(), when ffs_epfile_io()\nfails with an error other than -EIOCBQUEUED, the io_data structure (`p`) is\nfreed. However, for AIO operations, the kiocb cancel function was already\narmed and kiocb-\u003eprivate was set to `p`.\n\nIf a concurrent cancel operation (such as sys_io_cancel()) executes after\nffs_epfile_io() fails but before the function frees `p`, a Use-After-Free\ncan occur when the cancellation handler accesses the freed pointer.\n\nTo securely fix this race condition, we must properly un-arm the\ncancellation. Invoking `kiocb-\u003eki_complete()` does exactly this by\nacquiring `ctx-\u003ectx_lock` and safely removing the kiocb from the active\nsequence. In doing so, it ensures that a parallel io_cancel can no longer\ndiscover the kiocb, effectively closing the race window.\n\nWe then return -EIOCBQUEUED to notify the VFS layer that the kiocb has been\nconsumed and it should avoid attempting to complete the request again or\ntriggering subsequent completion handlers.",
"id": "GHSA-xqqx-xhmm-5h73",
"modified": "2026-09-21T15:31:43Z",
"published": "2026-09-16T12:30:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90044"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/153b5ecd29ed055562400bc17c91df3fd869b0ce"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4a2fb2d12b87b43724230abb52a1440617c7b6cc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b5f0e80a03e87bd932487e03248eae3ba3ed7b45"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e78dcb1f7ec271449c54984dc90c62a5ba272de7"
}
],
"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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