From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 17FE13A1E66; Mon, 29 Dec 2025 16:17:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767025070; cv=none; b=Ew6ejVSWu/wzLV49csmuttbhSz0/A97GK+WjgaOxMsfLK+b71gEEYZNGqdlR62mv0k0/7CFPqj0k67HHDgkedsx4QiRyQUopFacuViWvyNn2nZzIEIlSjgqgf9HL4sE+0VBqa+Ucfz/CN7cogtKK3/OAqq20PVbc/QUAVBPN8DU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767025070; c=relaxed/simple; bh=7PWx5e+ewSLmSWhRdYflGzw4iUKrxBVQq6LAHhOSqfM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=InLmyOsTZNBD3GwRT6byYrjIUn0ZqeA0vkSSZ1dTT3mK310Cjj5qxE/Dq8O3hHZygYZykYI+uqwrVwPMgroSnDqSjqOyITiaaem5jt1moRRRkNo/PBUO+wCb0IeuuRCedSf6mWxa/Mo7v1V2g/jxetdSpuXESeEE8MTWjE2SCAw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=J5BqnjtR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="J5BqnjtR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91F8BC4CEF7; Mon, 29 Dec 2025 16:17:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767025070; bh=7PWx5e+ewSLmSWhRdYflGzw4iUKrxBVQq6LAHhOSqfM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J5BqnjtRBtjF9szc7e0l+kb1tlCf8xjgedN6KFjJLbG77gW/VuncvUYSx4dJFFxlM /Y91pDMgJbJzs+zJRF93VNFZG5xNE0G32iZ5m4nXLRgW+0YLs4ekJFMEA9v5W8bbaS eYIaShvJwH72scXs2+RAshmWllrmMgLnAPl+P6s0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jamal Hadi Salim , Victor Nogueira , Petr Machata , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 083/430] net/sched: ets: Remove drr class from the active list if it changes to strict Date: Mon, 29 Dec 2025 17:08:05 +0100 Message-ID: <20251229160727.417783099@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251229160724.139406961@linuxfoundation.org> References: <20251229160724.139406961@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Victor Nogueira [ Upstream commit b1e125ae425aba9b45252e933ca8df52a843ec70 ] 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 Fixes: cd9b50adc6bb9 ("net/sched: ets: fix crash when flipping from 'strict' to 'quantum'") Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Reviewed-by: Petr Machata Link: https://patch.msgid.link/20251208190125.1868423-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_ets.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sched/sch_ets.c b/net/sched/sch_ets.c index ae46643e596d3..306e046276d46 100644 --- a/net/sched/sch_ets.c +++ b/net/sched/sch_ets.c @@ -664,6 +664,10 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt, q->classes[i].deficit = quanta[i]; } } + for (i = q->nstrict; i < nstrict; i++) { + if (cl_is_active(&q->classes[i])) + list_del_init(&q->classes[i].alist); + } WRITE_ONCE(q->nstrict, nstrict); memcpy(q->prio2band, priomap, sizeof(priomap)); -- 2.51.0