--- id: CVE-2025-68815 title: 'net/sched: ets: Remove drr class from the active list if it changes to strict' summary: |- In the Linux kernel, the following vulnerability has been resolved: net/sched: ets: Remove drr class from the active list if it changes to strict Whenever a user issues an ets qdisc change command, transforming a drr class into a stric… severity: high cvss: 7.8 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H' cvssSource: cna vendor: Linux product: Linux affected: - >- Linux >= f517335a61ff8037b18ba1b0a002c1f82926a934 < 58fdce6bc005e964f1dbc3ca716f5fe0f68839a2 - >- Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 02783a37cb1c0a2bd9fcba4ff1b81e6e209c7d87 - >- Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 8067db5c95aab9461d23117679338cd8869831fa - >- Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 2f125ebe47d6369e562f3cbd9b6227cff51eaf34 - >- Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < cca2ed931b734fe48139bc6f020e47367346630f - >- Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 43d9a530c8c094d137159784e7c951c65f11ec6c - >- Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < b1e125ae425aba9b45252e933ca8df52a843ec70 - Linux d05330672afe2e142ba97e63bd7c1faef76781bb - Linux >= 5.10.62 < 5.10.248 - Linux >= 5.13.14 < 5.14 - Linux 5.14 ssvc: exploitation: none automatable: 'no' technicalImpact: total timestamp: '2026-10-16T15:05:26.883019Z' published: '2026-01-13' updated: '2026-10-16' sourceUpdated: '2026-10-16T15:09:45.457Z' source: CVEORG sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-68815' references: - url: 'https://git.kernel.org/stable/c/58fdce6bc005e964f1dbc3ca716f5fe0f68839a2' - url: 'https://git.kernel.org/stable/c/02783a37cb1c0a2bd9fcba4ff1b81e6e209c7d87' - url: 'https://git.kernel.org/stable/c/8067db5c95aab9461d23117679338cd8869831fa' - url: 'https://git.kernel.org/stable/c/2f125ebe47d6369e562f3cbd9b6227cff51eaf34' - url: 'https://git.kernel.org/stable/c/cca2ed931b734fe48139bc6f020e47367346630f' - url: 'https://git.kernel.org/stable/c/43d9a530c8c094d137159784e7c951c65f11ec6c' - url: 'https://git.kernel.org/stable/c/b1e125ae425aba9b45252e933ca8df52a843ec70' tags: - cve.org epss: 0.00155 epssPercentile: 0.04184 ingestedAt: '2026-10-16T17:24:46.634Z' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: net/sched: ets: Remove drr class from the active list if it changes to strict Whenever a user issues an ets qdisc change command, transforming a drr class into a strict one, the ets code isn't checking whether that class was in the active list and removing it. This means that, if a user changes a strict class (which was in the active list) back to a drr one, that class will be added twice to the active list [1]. Doing so with the following commands: tc qdisc add dev lo root handle 1: ets bands 2 strict 1 tc qdisc add dev lo parent 1:2 handle 20: \ tbf rate 8bit burst 100b latency 1s tc filter add dev lo parent 1: basic classid 1:2 ping -c1 -W0.01 -s 56 127.0.0.1 tc qdisc change dev lo root handle 1: ets bands 2 strict 2 tc qdisc change dev lo root handle 1: ets bands 2 strict 1 ping -c1 -W0.01 -s 56 127.0.0.1 Will trigger the following splat with list debug turned on: [ 59.279014][ T365] ------------[ cut here ]------------ [ 59.279452][ T365] list_add double add: new=ffff88801d60e350, prev=ffff88801d60e350, next=ffff88801d60e2c0. [ 59.280153][ T365] WARNING: CPU: 3 PID: 365 at lib/list_debug.c:35 __list_add_valid_or_report+0x17f/0x220 [ 59.280860][ T365] Modules linked in: [ 59.281165][ T365] CPU: 3 UID: 0 PID: 365 Comm: tc Not tainted 6.18.0-rc7-00105-g7e9f13163c13-dirty #239 PREEMPT(voluntary) [ 59.281977][ T365] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 59.282391][ T365] RIP: 0010:__list_add_valid_or_report+0x17f/0x220 [ 59.282842][ T365] Code: 89 c6 e8 d4 b7 0d ff 90 0f 0b 90 90 31 c0 e9 31 ff ff ff 90 48 c7 c7 e0 a0 22 9f 48 89 f2 48 89 c1 4c 89 c6 e8 b2 b7 0d ff 90 <0f> 0b 90 90 31 c0 e9 0f ff ff ff 48 89 f7 48 89 44 24 10 4c 89 44 ... [ 59.288812][ T365] Call Trace: [ 59.289056][ T365] [ 59.289224][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.289546][ T365] ets_qdisc_change+0xd2b/0x1e80 [ 59.289891][ T365] ? __lock_acquire+0x7e7/0x1be0 [ 59.290223][ T365] ? __pfx_ets_qdisc_change+0x10/0x10 [ 59.290546][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.290898][ T365] ? __mutex_trylock_common+0xda/0x240 [ 59.291228][ T365] ? __pfx___mutex_trylock_common+0x10/0x10 [ 59.291655][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.291993][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.292313][ T365] ? trace_contention_end+0xc8/0x110 [ 59.292656][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.293022][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.293351][ T365] tc_modify_qdisc+0x63a/0x1cf0 Fix this by always checking and removing an ets class from the active list when changing it to strict. [1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/tree/net/sched/sch_ets.c?id=ce052b9402e461a9aded599f5b47e76bc727f7de#n663 ## Affected - `Linux >= f517335a61ff8037b18ba1b0a002c1f82926a934 < 58fdce6bc005e964f1dbc3ca716f5fe0f68839a2` - `Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 02783a37cb1c0a2bd9fcba4ff1b81e6e209c7d87` - `Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 8067db5c95aab9461d23117679338cd8869831fa` - `Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 2f125ebe47d6369e562f3cbd9b6227cff51eaf34` - `Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < cca2ed931b734fe48139bc6f020e47367346630f` - `Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < 43d9a530c8c094d137159784e7c951c65f11ec6c` - `Linux >= cd9b50adc6bb9ad3f7d244590a389522215865c4 < b1e125ae425aba9b45252e933ca8df52a843ec70` - `Linux d05330672afe2e142ba97e63bd7c1faef76781bb` - `Linux >= 5.10.62 < 5.10.248` - `Linux >= 5.13.14 < 5.14` - `Linux 5.14` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges.