GHSA-H95P-28WV-6WPP
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-19 18:32In the Linux kernel, the following vulnerability has been resolved:
can: isotp: serialize TX state transitions under so->rx_lock
The TX state machine (so->tx.state) is driven from three contexts: sendmsg() claiming and progressing a transfer, the RX path consuming Flow Control/echo frames, and two hrtimers timing out a stalled transfer. Mixing a lock-free cmpxchg() claim in sendmsg() with hrtimer_cancel() calls made under so->rx_lock elsewhere left windows where a frame or timer callback could act on a state that had already moved on, corrupting an unrelated transfer.
so->rx_lock now covers the full lifecycle of a TX claim: sendmsg() takes it to check so->tx.state is ISOTP_IDLE, switch it to ISOTP_SENDING, bump so->tx_gen and drain the previous transfer's timers - all as one critical section. isotp_rcv_fc()/isotp_rcv_cf() already run under this lock via isotp_rcv(), and isotp_rcv_echo() now takes it itself, so none of them can ever observe a transfer mid-claim. This also means a transfer can no longer be handed to sendmsg()'s cleanup paths (signal or send error) while another thread is concurrently claiming or finishing it, so those paths can cancel timers and reset the state unconditionally.
isotp_release() claims the socket the same way, so a racing sendmsg() sees a consistent ISOTP_SHUTDOWN and skips arming its timer or sending.
Only the hrtimer callbacks stay outside so->rx_lock, since they run under so->rx_lock's cancellation elsewhere and taking it themselves would deadlock. so->tx_gen lets them recognize whether the transfer they timed out is still the one currently active, so they don't report an error against a transfer that has since completed or been superseded.
{
"affected": [],
"aliases": [
"CVE-2026-72124"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:21:29Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: isotp: serialize TX state transitions under so-\u003erx_lock\n\nThe TX state machine (so-\u003etx.state) is driven from three contexts:\nsendmsg() claiming and progressing a transfer, the RX path consuming\nFlow Control/echo frames, and two hrtimers timing out a stalled\ntransfer. Mixing a lock-free cmpxchg() claim in sendmsg() with\nhrtimer_cancel() calls made under so-\u003erx_lock elsewhere left windows\nwhere a frame or timer callback could act on a state that had already\nmoved on, corrupting an unrelated transfer.\n\nso-\u003erx_lock now covers the full lifecycle of a TX claim: sendmsg()\ntakes it to check so-\u003etx.state is ISOTP_IDLE, switch it to\nISOTP_SENDING, bump so-\u003etx_gen and drain the previous transfer\u0027s\ntimers - all as one critical section. isotp_rcv_fc()/isotp_rcv_cf()\nalready run under this lock via isotp_rcv(), and isotp_rcv_echo() now\ntakes it itself, so none of them can ever observe a transfer mid-claim.\nThis also means a transfer can no longer be handed to sendmsg()\u0027s\ncleanup paths (signal or send error) while another thread is\nconcurrently claiming or finishing it, so those paths can cancel\ntimers and reset the state unconditionally.\n\nisotp_release() claims the socket the same way, so a racing sendmsg()\nsees a consistent ISOTP_SHUTDOWN and skips arming its timer or sending.\n\nOnly the hrtimer callbacks stay outside so-\u003erx_lock, since they run\nunder so-\u003erx_lock\u0027s cancellation elsewhere and taking it themselves\nwould deadlock. so-\u003etx_gen lets them recognize whether the transfer\nthey timed out is still the one currently active, so they don\u0027t\nreport an error against a transfer that has since completed or been\nsuperseded.",
"id": "GHSA-h95p-28wv-6wpp",
"modified": "2026-08-19T18:32:27Z",
"published": "2026-08-15T06:32:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72124"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0b05eca9589f609e2491b528dccf683168a4cda8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/377a8f500704da42ed86a4541ed930e9dcfdb2ea"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/37beb16e08cae94cc05840c7274225e3b0b38ae7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4f1fdf1a1c317bcac0c6b6c8e12642c9983de1ca"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6da8119e8dd542194103139812d1a4b7dcd1aedd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a7d90e7b5e75d7406c889fe36e9a61ee364a00cb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bbedeb67a9a684f2fb78c55bd3662c400526715e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cf070fe33bfbd1a4c21236078fadb35dd223a157"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
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Nomenclature
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