From patchwork Mon Jul 24 22:13:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Kanner X-Patchwork-Id: 13325376 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 87678125B7 for ; Mon, 24 Jul 2023 22:15:11 +0000 (UTC) Received: from mail-lj1-x235.google.com (mail-lj1-x235.google.com [IPv6:2a00:1450:4864:20::235]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 383F710CB; Mon, 24 Jul 2023 15:15:10 -0700 (PDT) Received: by mail-lj1-x235.google.com with SMTP id 38308e7fff4ca-2b95d5ee18dso71614301fa.1; Mon, 24 Jul 2023 15:15:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690236908; x=1690841708; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=VR5kr5/P9TZGbX0T3kYzKuPMSI9rX/Q6fFU/FogHPdo=; b=K7TpzLZSFTbsm+Zv7HTkwil6Z+M7WziaM9XD+4kQ3KbFBS+CPxNzQrS+qIdDt0xqjD ZhGlG7k4TswErdRWQr7kCaIbWRNbpdXCncvvhqnzcXjaYffiry/TwVlxasM+tMlTdHgr qv/H794OC21k3pldfu4o5v58DYcOGMwGjBqGDcATYR4s2vL/xxG0Zj+SZF7QW8RyVuYH gduR5At2PuMloDYbL/jjtySnPlkyb3YNhm89qFF68cu9gckTzkp5tboSnfRnAfmfUuxo lZHOf6lrOj+0h38jW1l+s+gB9LeY4cCWviRw1w+z3u23YshK5fPkSaE0SlbInmZmf2Ii bJQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690236908; x=1690841708; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=VR5kr5/P9TZGbX0T3kYzKuPMSI9rX/Q6fFU/FogHPdo=; b=KRUWh54Dr2fU/k4sokE/V7f9u+62lwpAbnL1PZxH+KdzrkoiBIOf2ypyL1gAcLe48i 5PKOKZOhb1KE5JExhC84/BASh9euNjugqD25nQcVHYBLZgFbXXUroTwXOkJvhzOmJKto hxhUYURcH6QHG5ME5QFZzdTiBa0lVae0i8L0UXdE8mglMS8V662ASa1YXHmLUs6wC12U QB6UvAWdV0q4b0ffiUdLG1guZclXjd/M5YsEQMV7cMXflPVdL0kXBahuH0b/zx7ghp8X mt5Avrsy0deVfODqXyk+Z8vu8OjUv35+JWGPOTEYuM5tsIbhRFlE4rW7I5hLLczrUP9Y BT8g== X-Gm-Message-State: ABy/qLYAGv0EKBN8wSN1CKiznm1TPLIx8Ix1501a7ByHIJ01+/Z1g6Hu E36wiyCKasvovHw4YLjJqFc= X-Google-Smtp-Source: APBJJlHb1Go1ALd4vfaDEL4yOJa8bVJ3Xvjgg/THhW+h1vUVM31EjGe8IiZLRMQz7JoQxb2F7Oqutw== X-Received: by 2002:a05:6512:3b84:b0:4fd:f84f:a729 with SMTP id g4-20020a0565123b8400b004fdf84fa729mr3185178lfv.11.1690236908188; Mon, 24 Jul 2023 15:15:08 -0700 (PDT) Received: from localhost.localdomain ([77.222.25.78]) by smtp.gmail.com with ESMTPSA id v2-20020a056512048200b004fba077e654sm2401130lfq.194.2023.07.24.15.15.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 15:15:07 -0700 (PDT) From: Andrew Kanner To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, jasowang@redhat.com, netdev@vger.kernel.org, brouer@redhat.com, linux-kernel@vger.kernel.org Cc: linux-kernel-mentees@lists.linuxfoundation.org, syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com, Andrew Kanner Subject: [PATCH 2/2] drivers: net: prevent tun_can_build_skb() to exceed xdp size limits Date: Tue, 25 Jul 2023 01:13:26 +0300 Message-Id: <20230724221326.384-2-andrew.kanner@gmail.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20230724221326.384-1-andrew.kanner@gmail.com> References: <20230724221326.384-1-andrew.kanner@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org Tested with syzkaller repro with reduced packet size. It was discovered that XDP_PACKET_HEADROOM is not checked in tun_can_build_skb(), although pad may be incremented in tun_build_skb(). Fixes: 7df13219d757 ("tun: reserve extra headroom only when XDP is set") Link: https://syzkaller.appspot.com/text?tag=ReproC&x=12b2593ea80000 Signed-off-by: Andrew Kanner --- drivers/net/tun.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 18ccbbe9830a..cdf2bd85b383 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1582,7 +1582,13 @@ static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile, static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile, int len, int noblock, bool zerocopy, int *skb_xdp) { - if (SKB_DATA_ALIGN(len + TUN_RX_PAD) + + int pad = TUN_RX_PAD; + struct bpf_prog *xdp_prog = rcu_dereference(tun->xdp_prog); + + if (xdp_prog) + pad += XDP_PACKET_HEADROOM; + + if (SKB_DATA_ALIGN(len + pad) + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE) { *skb_xdp = 0; return false;