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 147C22F851; Mon, 23 Mar 2026 14:53:31 +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=1774277611; cv=none; b=oxE5m8FSRvM9Cqce/OFp5jcr6R7g/7Py9cgUma5UecVisRPixxcXSNVekUL3RWb6/Uis+qEumgNArInzjBPPe2kxMvn2hureindXLm36oG3sT3eHkDO1+rImveOjP4erldGN2vBgei/hK73hzQ1Qv4+boNyJSP3dQO/k00elUSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774277611; c=relaxed/simple; bh=5AdltIY4u1pF7XL7Onp5YDDBwCeOOOgXtOjz3y85PNs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=on2NlVjkLzBJjogCqM/3a9e5uyLh6D6NFpACA8OVb1J6jq/C7KQ93L7xHb6fNPlVv/QotOrVYcROccC/j6o7/Bozqz95U7AMlxl6DdLuV8OAebGIL2bh8tO43YPc89CEEuWLxeqO/NQmlMyqyQ1h3qfeJwEI7WMwJdtZW4g+c7I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=knGK8ufn; 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="knGK8ufn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93F6EC4CEF7; Mon, 23 Mar 2026 14:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774277611; bh=5AdltIY4u1pF7XL7Onp5YDDBwCeOOOgXtOjz3y85PNs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=knGK8ufnSLX11FozD+FWbfWF9rz1r5Dd8lYz4Lsc93xTVN+2Zp3jurjTS+wA1u8Rz QXp13UV3iw1EtZRpioffUpdKZwW8UOtvX/n5Fy8Y+HQweV6cZ+qHz3M9IIHMHhmHKS fXTczIFWsv4ZGRo6Z/tT++T0/GUalRgM7lWHdJ58= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+10cc7f13760b31bd2e61@syzkaller.appspotmail.com, =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Kohei Enju , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.6 025/567] bpf: Fix stack-out-of-bounds write in devmap Date: Mon, 23 Mar 2026 14:39:05 +0100 Message-ID: <20260323134534.392315053@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134533.749096647@linuxfoundation.org> References: <20260323134533.749096647@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-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: Kohei Enju [ Upstream commit b7bf516c3ecd9a2aae2dc2635178ab87b734fef1 ] get_upper_ifindexes() iterates over all upper devices and writes their indices into an array without checking bounds. Also the callers assume that the max number of upper devices is MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack, but that assumption is not correct and the number of upper devices could be larger than MAX_NEST_DEV (e.g., many macvlans), causing a stack-out-of-bounds write. Add a max parameter to get_upper_ifindexes() to avoid the issue. When there are too many upper devices, return -EOVERFLOW and abort the redirect. To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS. Then send a packet to the device to trigger the XDP redirect path. Reported-by: syzbot+10cc7f13760b31bd2e61@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/698c4ce3.050a0220.340abe.000b.GAE@google.com/T/ Fixes: aeea1b86f936 ("bpf, devmap: Exclude XDP broadcast to master device") Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Kohei Enju Link: https://lore.kernel.org/r/20260225053506.4738-1-kohei@enjuk.jp Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/devmap.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 5f2356b47b2dd..3bdec239be610 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -577,18 +577,22 @@ static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifin } /* Get ifindex of each upper device. 'indexes' must be able to hold at - * least MAX_NEST_DEV elements. - * Returns the number of ifindexes added. + * least 'max' elements. + * Returns the number of ifindexes added, or -EOVERFLOW if there are too + * many upper devices. */ -static int get_upper_ifindexes(struct net_device *dev, int *indexes) +static int get_upper_ifindexes(struct net_device *dev, int *indexes, int max) { struct net_device *upper; struct list_head *iter; int n = 0; netdev_for_each_upper_dev_rcu(dev, upper, iter) { + if (n >= max) + return -EOVERFLOW; indexes[n++] = upper->ifindex; } + return n; } @@ -604,7 +608,11 @@ int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx, int err; if (exclude_ingress) { - num_excluded = get_upper_ifindexes(dev_rx, excluded_devices); + num_excluded = get_upper_ifindexes(dev_rx, excluded_devices, + ARRAY_SIZE(excluded_devices) - 1); + if (num_excluded < 0) + return num_excluded; + excluded_devices[num_excluded++] = dev_rx->ifindex; } @@ -722,7 +730,11 @@ int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb, int err; if (exclude_ingress) { - num_excluded = get_upper_ifindexes(dev, excluded_devices); + num_excluded = get_upper_ifindexes(dev, excluded_devices, + ARRAY_SIZE(excluded_devices) - 1); + if (num_excluded < 0) + return num_excluded; + excluded_devices[num_excluded++] = dev->ifindex; } -- 2.51.0