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 7ED501EA84; Wed, 4 Feb 2026 14:42:59 +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=1770216179; cv=none; b=na8xNp3zd9BTRptSV/NwLDCXvHQzfprfvp+Mh8N4IrV8d/0qVjd2LbwMhgWvAIpKZ8vbf2STz/ueIdO4jvVekWy4xkQlvGR4nGtw29YUC5CqVy/97l+PIOV0g8nJ11SlXxLPeqJ30GlPDQPghvQpGdnSTX0uzsfgQs6oDmlDisU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770216179; c=relaxed/simple; bh=rhDF6y1K2DXFq7nyyTCSM8GXTMo6w8k9Lfsw8jE5MZs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sTwMOlWVqjVpLpXr/GYKPLGU8k0bmF3R9riIan8Y7txCVATag38PNUdo7mtgrcjFT/vRV8zEvy4+y8x/f8eZYYTEtiRxV6YAwK7qgaB0P46rMvuYXNq9uUKrUUijQpzOvdqXTCLmvtocJjJirV31d5zRBivmWTHFGKuVjEGydfA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oUKj0sBn; 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="oUKj0sBn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90E83C116C6; Wed, 4 Feb 2026 14:42:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770216179; bh=rhDF6y1K2DXFq7nyyTCSM8GXTMo6w8k9Lfsw8jE5MZs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oUKj0sBnMEiP6CVvVoB9tfrpYBH+dTtfjfQSPj+MJFM4mNPAZ/Kikx8rPwWYgWZAY 2XVFJ2Gog9X/pqQ0vQkzAmLZujrRDWdgxFaBbNApzOxuIBhehxsKo0T6R24kGQ5OIh Qwn3IG0qbYBEZEW6p+gy9aV5o/O0WUKkeELWJjEA= 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 5.10 011/161] net/sched: sch_qfq: do not free existing class in qfq_change_class() Date: Wed, 4 Feb 2026 15:37:54 +0100 Message-ID: <20260204143852.169872461@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260204143851.755002596@linuxfoundation.org> References: <20260204143851.755002596@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: 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 34a6c4ec9a157..9751de2d95e78 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -532,8 +532,10 @@ 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