{"id":"DEBIAN-CVE-2021-4454","details":"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] \t\t\t\tj1939_session_completed \t\t\t\tj1939_session_deactivate \t\t\t\tWARN_ON_ONCE(kref \u003c 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","modified":"2026-09-15T09:02:34.758486303Z","published":"2025-03-27T17:15:35.820Z","upstream":["CVE-2021-4454"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2021-4454"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.11-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4454.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.11-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4454.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.11-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4454.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}