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 5B634237162; Tue, 17 Jun 2025 16:11:54 +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=1750176714; cv=none; b=MGI5oSz4gqiDeAnShUcsNUFADP/qYk2GPzluUi2y9YiO1TRsTqgJZED4EuXRZOuidcQd6jday3p/6afALkAsxLC+sf66hpdZKyL2F/bg+zgQ4a/M95YCTY+U1E0ldXwRm5nMeE0HOX6UiIZYBntqJkwEqimxC/n3ZO6HNa5apjg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750176714; c=relaxed/simple; bh=X8CnlJLkfooNguZV9X9T1njuB1z/WgT8U2TOrDcaTsE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=nN0NRlHWeZz5IoxsYpv4CCvmnDgyYKtcwmuJbJmhcSjzk3PMFk9BpKkVuie3pHRwD9tfipevZn33Z4gJGQGXQd+b9f1JEgpYLr4uxk+CffLXMgQmEk8aSd9kIp3PukOrY8AgVBZi3gHl/IoJ5aKYZwIWTXQTFHmWlfHkhoGLXkk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mjRkaKot; 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="mjRkaKot" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C0495C4CEE3; Tue, 17 Jun 2025 16:11:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750176714; bh=X8CnlJLkfooNguZV9X9T1njuB1z/WgT8U2TOrDcaTsE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mjRkaKotABopyKvwt+tV8eW4lVZ6hXaznirK7pPIbar4SBc8LEZafFQcV0jrMKk+A pVDZu1UvIrAiUWn7J9unMrMFkSsLyj6kB1/+4fu5Lz6hFSQWW5qLiel+koYaOn8C71 mYb5wG/UCIErx1zlXCnO9X1HH38Fxujwlnr/50P0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marcus Wichelmann , Eric Dumazet , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 306/356] net_sched: sch_sfq: fix a potential crash on gso_skb handling Date: Tue, 17 Jun 2025 17:27:01 +0200 Message-ID: <20250617152350.489421654@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250617152338.212798615@linuxfoundation.org> References: <20250617152338.212798615@linuxfoundation.org> User-Agent: quilt/0.68 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 82ffbe7776d0ac084031f114167712269bf3d832 ] SFQ has an assumption of always being able to queue at least one packet. However, after the blamed commit, sch->q.len can be inflated by packets in sch->gso_skb, and an enqueue() on an empty SFQ qdisc can be followed by an immediate drop. Fix sfq_drop() to properly clear q->tail in this situation. Tested: ip netns add lb ip link add dev to-lb type veth peer name in-lb netns lb ethtool -K to-lb tso off # force qdisc to requeue gso_skb ip netns exec lb ethtool -K in-lb gro on # enable NAPI ip link set dev to-lb up ip -netns lb link set dev in-lb up ip addr add dev to-lb 192.168.20.1/24 ip -netns lb addr add dev in-lb 192.168.20.2/24 tc qdisc replace dev to-lb root sfq limit 100 ip netns exec lb netserver netperf -H 192.168.20.2 -l 100 & netperf -H 192.168.20.2 -l 100 & netperf -H 192.168.20.2 -l 100 & netperf -H 192.168.20.2 -l 100 & Fixes: a53851e2c321 ("net: sched: explicit locking in gso_cpu fallback") Reported-by: Marcus Wichelmann Closes: https://lore.kernel.org/netdev/9da42688-bfaa-4364-8797-e9271f3bdaef@hetzner-cloud.de/ Signed-off-by: Eric Dumazet Reviewed-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20250606165127.3629486-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_sfq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 002941d35b643..d564675a8be4d 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -310,7 +310,10 @@ static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free) /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */ x = q->tail->next; slot = &q->slots[x]; - q->tail->next = slot->next; + if (slot->next == x) + q->tail = NULL; /* no more active slots */ + else + q->tail->next = slot->next; q->ht[slot->hash] = SFQ_EMPTY_SLOT; goto drop; } -- 2.39.5