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 8A3BD3C1988; Thu, 15 Jan 2026 17:48:17 +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=1768499297; cv=none; b=ulvbYmPpn6ZIDolIAfkEYRShFW1SSd7W3Opjzc3rwMLI6INkKSCW4UIGRQkADdleI3oHxU21M1AOoF2RPD6Pqqh7NBFA4dkiNrji1bZMRR4G9Gt6OYKdbYSekUMbhC4/dqHfnaBe9+uw3GPGkGPrj1uNvQ6PpjZbJWuXzuuzaKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499297; c=relaxed/simple; bh=mCo3k/hLTp5ZzK8bMKtmk7TO61NjThBSQsvDPGNkriI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Pvrb9pOgpGSH0jRYApprDn0HrHsgMxTYbaglNRPObzJFUmHndm7Ky7+vpSEoo7yLiHvAdh95WcS1Yi1fMIHFDiTOSOj7M/RDeLJgdkWEfvS0T+HvWAjcgNgFbV9L6U85MHWSb40cLqIG8+yVaCLxY9X+C9tmtpYj4I+bsjGok2Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=O7zq85Nl; 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="O7zq85Nl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC2ADC16AAE; Thu, 15 Jan 2026 17:48:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768499297; bh=mCo3k/hLTp5ZzK8bMKtmk7TO61NjThBSQsvDPGNkriI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O7zq85Nl8A0xF4Y/wqy46UoTGdlvXpN9n3wVb/KbiEKWgpAqMszrrD6pzJue9OfqL ytZWlHzLIYG9JfBeLxQWRxMxQ3QwYtv5sqBFuSKml2vnqPY0yy6rMxDeWdcKe5/w2u xB2fgAdv1HLph80AHuIFTb/QmzdabNAi6qciP0XY= 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 5.10 178/451] net/sched: ets: Remove drr class from the active list if it changes to strict Date: Thu, 15 Jan 2026 17:46:19 +0100 Message-ID: <20260115164237.344753744@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164230.864985076@linuxfoundation.org> References: <20260115164230.864985076@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-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 ad5d9b27670ca..c939937b2b81d 100644 --- a/net/sched/sch_ets.c +++ b/net/sched/sch_ets.c @@ -677,6 +677,10 @@ 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