{"cve":"CVE-2025-38684","nvd":{"published":"2025-09-04T16:15:36.210","modified":"2026-10-19T21:10:00.160","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: ets: use old 'nbands' while purging unused classes\n\nShuang reported sch_ets test-case [1] crashing in ets_class_qlen_notify()\nafter recent changes from Lion [2]. The problem is: in ets_qdisc_change()\nwe purge unused DWRR queues; the value of 'q->nbands' is the new one, and\nthe cleanup should be done with the old one. The problem is here since my\nfirst attempts to fix ets_qdisc_change(), but it surfaced again after the\nrecent qdisc len accounting fixes. Fix it purging idle DWRR queues before\nassigning a new value of 'q->nbands', so that all purge operations find a\nconsistent configuration:\n\n - old 'q->nbands' because it's needed by ets_class_find()\n - old 'q->nstrict' because it's needed by ets_class_is_strict()\n\n BUG: kernel NULL pointer dereference, address: 0000000000000000\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0000 [#1] SMP NOPTI\n CPU: 62 UID: 0 PID: 39457 Comm: tc Kdump: loaded Not tainted 6.12.0-116.el10.x86_64 #1 PREEMPT(voluntary)\n Hardware name: Dell Inc. PowerEdge R640/06DKY5, BIOS 2.12.2 07/09/2021\n RIP: 0010:__list_del_entry_valid_or_report+0x4/0x80\n Code: ff 4c 39 c7 0f 84 39 19 8e ff b8 01 00 00 00 c3 cc cc cc cc 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <48> 8b 17 48 8b 4f 08 48 85 d2 0f 84 56 19 8e ff 48 85 c9 0f 84 ab\n RSP: 0018:ffffba186009f400 EFLAGS: 00010202\n RAX: 00000000000000d6 RBX: 0000000000000000 RCX: 0000000000000004\n RDX: ffff9f0fa29b69c0 RSI: 0000000000000000 RDI: 0000000000000000\n RBP: ffffffffc12c2400 R08: 0000000000000008 R09: 0000000000000004\n R10: ffffffffffffffff R11: 0000000000000004 R12: 0000000000000000\n R13: ffff9f0f8cfe0000 R14: 0000000000100005 R15: 0000000000000000\n FS:  00007f2154f37480(0000) GS:ffff9f269c1c0000(0000) knlGS:0000000000000000\n CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 0000000000000000 CR3: 00000001530be001 CR4: 00000000007726f0\n DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n PKRU: 55555554\n Call Trace:\n  <TASK>\n  ets_class_qlen_notify+0x65/0x90 [sch_ets]\n  qdisc_tree_reduce_backlog+0x74/0x110\n  ets_qdisc_change+0x630/0xa40 [sch_ets]\n  __tc_modify_qdisc.constprop.0+0x216/0x7f0\n  tc_modify_qdisc+0x7c/0x120\n  rtnetlink_rcv_msg+0x145/0x3f0\n  netlink_rcv_skb+0x53/0x100\n  netlink_unicast+0x245/0x390\n  netlink_sendmsg+0x21b/0x470\n  ____sys_sendmsg+0x39d/0x3d0\n  ___sys_sendmsg+0x9a/0xe0\n  __sys_sendmsg+0x7a/0xd0\n  do_syscall_64+0x7d/0x160\n  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n RIP: 0033:0x7f2155114084\n Code: 89 02 b8 ff ff ff ff eb bb 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 80 3d 25 f0 0c 00 00 74 13 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89\n RSP: 002b:00007fff1fd7a988 EFLAGS: 00000202 ORIG_RAX: 000000000000002e\n RAX: ffffffffffffffda RBX: 0000560ec063e5e0 RCX: 00007f2155114084\n RDX: 0000000000000000 RSI: 00007fff1fd7a9f0 RDI: 0000000000000003\n RBP: 00007fff1fd7aa60 R08: 0000000000000010 R09: 000000000000003f\n R10: 0000560ee9b3a010 R11: 0000000000000202 R12: 00007fff1fd7aae0\n R13: 000000006891ccde R14: 0000560ec063e5e0 R15: 00007fff1fd7aad0\n  </TASK>\n\n [1] https://lore.kernel.org/netdev/e08c7f4a6882f260011909a868311c6e9b54f3e4.1639153474.git.dcaratti@redhat.com/\n [2] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/5b3b346bc4c2aa2c428735438a11989d251f32f1","https://git.kernel.org/stable/c/84a24fb446ee07b22b64aae6f0e3f4a38266310a","https://git.kernel.org/stable/c/87c6efc5ce9c126ae4a781bc04504b83780e3650","https://git.kernel.org/stable/c/970c1c731c4ede46d05f5b0355724d1e400cfbca","https://git.kernel.org/stable/c/97ec167cd2e8a81a2d87331a2ed92daf007542c8"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-38684","score":0.00176,"percentile":0.07039,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}