CVE-2021-4454
can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate The conclusion "j1939_session_deactivate() should be called with a session ref-count of at least 2" is incorrect. In some concurrent scenarios, j1939_session_deactivate can be called with the session ref-count less than 2. But there is not any problem because it will check the session active state before session putting in j1939_session_deactivate_locked(). Here is the concurrent scenario of the problem reported by syzbot and my reproduction log. cpu0 cpu1 j1939_xtp_rx_eoma j1939_xtp_rx_abort_one j1939_session_get_by_addr [kref == 2] j1939_session_get_by_addr [kref == 3] j1939_session_deactivate [kref == 2] j1939_session_put [kref == 1] j1939_session_completed j1939_session_deactivate WARN_ON_ONCE(kref < 2) ===================================================== WARNING: CPU: 1 PID: 21 at net/can/j1939/transport.c:1088 j1939_session_deactivate+0x5f/0x70 CPU: 1 PID: 21 Comm: ksoftirqd/1 Not tainted 5.14.0-rc7+ #32 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 RIP: 0010:j1939_session_deactivate+0x5f/0x70 Call Trace: j1939_session_deactivate_activate_next+0x11/0x28 j1939_xtp_rx_eoma+0x12a/0x180 j1939_tp_recv+0x4a2/0x510 j1939_can_recv+0x226/0x380 can_rcv_filter+0xf8/0x220 can_receive+0x102/0x220 ? process_backlog+0xf0/0x2c0 can_rcv+0x53/0xf0 __netif_receive_skb_one_core+0x67/0x90 ? process_backlog+0x97/0x2c0 __netif_receive_skb+0x22/0x80
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.59% · top 52% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- affected 7eef18c0479ba5d9f54fba30cd77c233ebca3eb1 – < 6950df42a03c9ac9290503ced3f371199cb68fa9
- affected 55dd22c5d029423f513fd849e633adf0e9c10d0c – < b6d44072117bba057d50f7a2f96e5d070c65926d
- affected 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 – < 9ab896775f98ff54b68512f345eed178bf961084
- affected 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 – < 1740a1e45eee65099a92fb502e1e67e63aad277d
- affected 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 – < d0553680f94c49bbe0e39eb50d033ba563b4212d
- affected 5e1fc537c1be332aef9621ca9146aeb3ba59522f
- affected 5.4.138 – < 5.4.232
- affected 5.10.56 – < 5.10.168
- affected 5.13.8 – < 5.14
- affected 5.14
- unaffected < 5.14
- unaffected 5.4.232 – ≤ 5.4.*
- unaffected 5.10.168 – ≤ 5.10.*
- unaffected 5.15.93 – ≤ 5.15.*
- unaffected 6.1.11 – ≤ 6.1.*
- unaffected 6.2 – ≤ *
References (5)
- https://git.kernel.org/stable/c/6950df42a03c9ac9290503ced3f371199cb68fa9 (opens in a new tab)
- https://git.kernel.org/stable/c/b6d44072117bba057d50f7a2f96e5d070c65926d (opens in a new tab)
- https://git.kernel.org/stable/c/9ab896775f98ff54b68512f345eed178bf961084 (opens in a new tab)
- https://git.kernel.org/stable/c/1740a1e45eee65099a92fb502e1e67e63aad277d (opens in a new tab)
- https://git.kernel.org/stable/c/d0553680f94c49bbe0e39eb50d033ba563b4212d (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://trackcve.app/cve/CVE-2021-4454)Record last updated .