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 9AF812DF134; Wed, 21 Jan 2026 18:28:03 +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=1769020083; cv=none; b=koqlOZcKj0UfN6T2BkMnuTT5KnFkMME95N8+ZjKw0G+/y4yhkbu2c6RTFzE7wCpsYd6Zn+tHfcYoAE3N7qrBHxoW4QiUxL98c60FpdHTnXI/mKrKIC7zWNpjvqdOJ49hQhimnKgQliHFYxNLeXdR1LXn9bPjEVsgWctm2xFutdw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769020083; c=relaxed/simple; bh=xAjOZQFRZcNMFjFGyYT47XKNfB2Q/20V9rAhQBpPSdk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cB6mN7r3/YWa02oera7cVnPzKfJoxle3V/vKlzjtuyLgk0RxgVdqZA+esudMTjpEmKj4v/iqVYlK91bwJ2aEv4nOau+xKyKAbgBrPi+WHGDbV4QLU6joWdXGelmEIQINTZ88El4KEe3He37/Slg5qHuEHejm3nI/KO6coo3mE9E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=agwHDHYO; 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="agwHDHYO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BEEEEC4CEF1; Wed, 21 Jan 2026 18:28:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1769020083; bh=xAjOZQFRZcNMFjFGyYT47XKNfB2Q/20V9rAhQBpPSdk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=agwHDHYOg72IHBG6L1awUL0PIKO9ONx/UrdNvyFXkHpGnNuTLCugzCFRBfdDsuxeF Q+7Qmr7FKTWLzy+lO6fQbJino1FhN1zZhrsOQjzPE1I5hu6fzDDjjzDOr3mMiegshl cJQZ5CXtTg32JtroWExLrJqdDt4RqZBNpLqiwPX8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+07f3f38f723c335f106d@syzkaller.appspotmail.com, Eric Dumazet , Jamal Hadi Salim , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 054/198] net/sched: sch_qfq: do not free existing class in qfq_change_class() Date: Wed, 21 Jan 2026 19:14:42 +0100 Message-ID: <20260121181420.499363700@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260121181418.537774329@linuxfoundation.org> References: <20260121181418.537774329@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 3879cffd9d07aa0377c4b8835c4f64b4fb24ac78 ] Fixes qfq_change_class() error case. cl->qdisc and cl should only be freed if a new class and qdisc were allocated, or we risk various UAF. Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost") Reported-by: syzbot+07f3f38f723c335f106d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6965351d.050a0220.eaf7.00c5.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Reviewed-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260112175656.17605-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_qfq.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index a91a5bac8f737..9b16ad431028f 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -529,8 +529,10 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, return 0; destroy_class: - qdisc_put(cl->qdisc); - kfree(cl); + if (!existing) { + qdisc_put(cl->qdisc); + kfree(cl); + } return err; } -- 2.51.0