From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59ED6C433E0 for ; Sun, 28 Feb 2021 19:29:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22F5864E99 for ; Sun, 28 Feb 2021 19:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231484AbhB1T3B (ORCPT ); Sun, 28 Feb 2021 14:29:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49822 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231190AbhB1T25 (ORCPT ); Sun, 28 Feb 2021 14:28:57 -0500 Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61679C06174A; Sun, 28 Feb 2021 11:28:16 -0800 (PST) Received: by mail-lf1-x12a.google.com with SMTP id b1so11180733lfb.7; Sun, 28 Feb 2021 11:28:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:subject:from:to:cc:date:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=Adl6CK8nrXne88qZjWHiIGNkiXx3KmatImtubYveON0=; b=NIy12U1DZ+HecQB+s0dKuaQ8MY0WIQtPfCvN0jhQQi644mA6BgPphKx64u28+KsmOO Jr0swsC+egUsB+g9iXjxCBhuyAXdfKJoytyMoKlFdfQh16lzayvzksSCkMMfsr5vb9SB 4ipzML/jdATQ8Vmtp8RHYBvANiaXZGAvIMJ8gGWxZsTeXvVNVm3e/WN8OfnTY5OTbQiP 3zuBO+tOq0hLIa87gaeQnfaoyEOKVtVmnPbUxKrvjGhC4jh54+58HCBHxw580eBu/8Ca Ta6LVkZTrRbTlY4/h+MeYT25AHtfAO5yxmddvbK/6cvlOFI7MeG2lJ8zehXDp9ljYzPH RSoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=Adl6CK8nrXne88qZjWHiIGNkiXx3KmatImtubYveON0=; b=tkKiGqnJJhpfAzmm5GZr2XNpjn1XiyzdJZLFqYE0dAtAvJcsiq8WUdPoBK2u+9ee6r 9++ec4jmEY1dC5UjJkvwWg/0/Y6y/0p6T6UAlXK03X3CFok0xmkRPBkQ6zFNGfYLIYwc AqMmhNZLrgdYI0IvP74zDLeO4LF9mt4/a5z0EBnIY27B61C2IQkDhl5B4x+SrPACAiMF gqpM+z22j9GwDLit7iSnsEFL2TCvXugI84lhA3QgJ25bI3VzxHEc75DUEbxsETv0Q4RU Ps3CBoEEBNj4BctAJpvxyGp0RGp/hFFrKqbwb8BLBqbC+2oM9XrrzmyNaiZYxxu508dx 0rzg== X-Gm-Message-State: AOAM532yqhXm8iFmFuVnoaGfz/S1bEcJ7+MSbILg4RJaMtec43J0e6Yc i8gEFqcHm1wQuGtIVWQraB3wA/21fnzKBVpDre0= X-Google-Smtp-Source: ABdhPJyeJ+bAyav9aNrEq2G3W2/X3qYzwOYIAtNWne6+ZAZ4Z0kBFqRSQ/kbNdKSWIMdoG352d+Jqg== X-Received: by 2002:a19:c14a:: with SMTP id r71mr7355718lff.358.1614540494867; Sun, 28 Feb 2021 11:28:14 -0800 (PST) Received: from pskrgag-home ([94.103.235.167]) by smtp.gmail.com with ESMTPSA id a9sm2215955ljn.129.2021.02.28.11.28.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 Feb 2021 11:28:14 -0800 (PST) Message-ID: <47681a0b629ac0efb2ce0d92c3181db08e5ea3c8.camel@gmail.com> Subject: Re: [PATCH v3] net/core/skbuff: fix passing wrong size to __alloc_skb From: Pavel Skripkin To: Alexander Lobakin Cc: davem@davemloft.net, linmiaohe@huawei.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+80dccaee7c6630fa9dcf@syzkaller.appspotmail.com Date: Sun, 28 Feb 2021 22:28:13 +0300 In-Reply-To: <20210228181440.1715-1-alobakin@pm.me> References: <20210227110306.13360-1-alobakin@pm.me> <20210227175114.28645-1-paskripkin@gmail.com> <20210228181440.1715-1-alobakin@pm.me> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, thanks for reply! > From: Pavel Skripkin > Date: Sat, 27 Feb 2021 20:51:14 +0300 > > Hi, > > > syzbot found WARNING in __alloc_pages_nodemask()[1] when order >= > > MAX_ORDER. > > It was caused by __netdev_alloc_skb(), which doesn't check len > > value after adding NET_SKB_PAD. > > Order will be >= MAX_ORDER and passed to __alloc_pages_nodemask() > > if size > KMALLOC_MAX_SIZE. > > Same happens in __napi_alloc_skb. > > > > static void *kmalloc_large_node(size_t size, gfp_t flags, int node) > > { > > struct page *page; > > void *ptr = NULL; > > unsigned int order = get_order(size); > > ... > > page = alloc_pages_node(node, flags, order); > > ... > > > > [1] WARNING in __alloc_pages_nodemask+0x5f8/0x730 > > mm/page_alloc.c:5014 > > Call Trace: > > __alloc_pages include/linux/gfp.h:511 [inline] > > __alloc_pages_node include/linux/gfp.h:524 [inline] > > alloc_pages_node include/linux/gfp.h:538 [inline] > > kmalloc_large_node+0x60/0x110 mm/slub.c:3999 > > __kmalloc_node_track_caller+0x319/0x3f0 mm/slub.c:4496 > > __kmalloc_reserve net/core/skbuff.c:150 [inline] > > __alloc_skb+0x4e4/0x5a0 net/core/skbuff.c:210 > > __netdev_alloc_skb+0x70/0x400 net/core/skbuff.c:446 > > netdev_alloc_skb include/linux/skbuff.h:2832 [inline] > > qrtr_endpoint_post+0x84/0x11b0 net/qrtr/qrtr.c:442 > > qrtr_tun_write_iter+0x11f/0x1a0 net/qrtr/tun.c:98 > > call_write_iter include/linux/fs.h:1901 [inline] > > new_sync_write+0x426/0x650 fs/read_write.c:518 > > vfs_write+0x791/0xa30 fs/read_write.c:605 > > ksys_write+0x12d/0x250 fs/read_write.c:658 > > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Ah, by the way. Have you tried to seek for the root cause, why > a request for such insanely large (at least 4 Mib) skb happens > in QRTR? I don't believe it's intended to be like this. > Now I feel that silencing this error with early return isn't > really correct approach for this. Yeah, i figured it out. Syzbot provides reproducer for thig bug: void loop(void) { intptr_t res = 0; memcpy((void*)0x20000000, "/dev/qrtr-tun\000", 14); res = syscall(__NR_openat, 0xffffffffffffff9cul, 0x20000000ul, 1ul, 0); if (res != -1) r[0] = res; memcpy((void*)0x20000040, "\x02", 1); syscall(__NR_write, r[0], 0x20000040ul, 0x400000ul); } So, simply it writes to /dev/qrtr-tun 0x400000 bytes. In qrtr_tun_write_iter there is a check, that the length is smaller than KMALLOC_MAX_VSIZE. Then the length is passed to __netdev_alloc_skb, where it becomes more than KMALLOC_MAX_VSIZE. > > > Reported-by: syzbot+80dccaee7c6630fa9dcf@syzkaller.appspotmail.com > > Signed-off-by: Pavel Skripkin > > > > --- > > Changes from v3: > > * Removed Change-Id and extra tabs in net/core/skbuff.c > > > > Changes from v2: > > * Added length check to __napi_alloc_skb > > * Added unlikely() in checks > > > > Change from v1: > > * Added length check to __netdev_alloc_skb > > --- > > net/core/skbuff.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > > index 785daff48030..ec7ba8728b61 100644 > > --- a/net/core/skbuff.c > > +++ b/net/core/skbuff.c > > @@ -443,6 +443,9 @@ struct sk_buff *__netdev_alloc_skb(struct > > net_device *dev, unsigned int len, > > if (len <= SKB_WITH_OVERHEAD(1024) || > > len > SKB_WITH_OVERHEAD(PAGE_SIZE) || > > (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) { > > + if (unlikely(len > KMALLOC_MAX_SIZE)) > > + return NULL; > > + > > skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, > > NUMA_NO_NODE); > > if (!skb) > > goto skb_fail; > > @@ -517,6 +520,9 @@ struct sk_buff *__napi_alloc_skb(struct > > napi_struct *napi, unsigned int len, > > if (len <= SKB_WITH_OVERHEAD(1024) || > > len > SKB_WITH_OVERHEAD(PAGE_SIZE) || > > (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) { > > + if (unlikely(len > KMALLOC_MAX_SIZE)) > > + return NULL; > > + > > skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, > > NUMA_NO_NODE); > > if (!skb) > > goto skb_fail; > > -- > > 2.25.1 > > Thanks, > Al > With regards, Pavel Skripkin