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[2620:137:e000::1:20]) by mx.google.com with ESMTP id by23-20020a170906a2d700b00993325b159csi9494167ejb.659.2023.08.01.17.41.06; Tue, 01 Aug 2023 17:41:34 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=XaniT5r6; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232155AbjHAWJt (ORCPT + 99 others); Tue, 1 Aug 2023 18:09:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231397AbjHAWJp (ORCPT ); Tue, 1 Aug 2023 18:09:45 -0400 Received: from mail-lj1-x236.google.com (mail-lj1-x236.google.com [IPv6:2a00:1450:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3BD926AA; Tue, 1 Aug 2023 15:09:28 -0700 (PDT) Received: by mail-lj1-x236.google.com with SMTP id 38308e7fff4ca-2b9d3dacb33so67870921fa.1; Tue, 01 Aug 2023 15:09:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690927767; x=1691532567; 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=dSpmN52R4zvJ1S+i6B6OGYZwzIS1/5yW5wWragBrFA0=; b=XaniT5r6suwpR7jjJvcmJOh5zqRrMucOLpNrGei5m8doTVhDnRJgRnqGz4phmQsdLD nzXezpAZXhLt7Ph6121T6v0zExcd2XJdiF0GOMSC9PuIx2pHAlbb9tPR/UWGlfRVH3wZ ejpBzUQxLFfJHTa6zEpY1J3TZ7qAdMzgPMTQy7Y8kiCABW+2fACQY8cT8kIl2w3pw8Ht oAHfupQqrwFQq+i7VgGvg209uSclzOJSLpWRYGz7WxUEQGpYd0qyJyv9t3HZsPlKCiTq pkKAtjAliHu35zGMGRlAcA7QJwo7Azk84djCD7yXwzJZPfuSqbIRYDP5AxjDBsPqVIkL 4UwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690927767; x=1691532567; 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=dSpmN52R4zvJ1S+i6B6OGYZwzIS1/5yW5wWragBrFA0=; b=UDQJqeacLJFC2QnxmBWeitBbtsbZj8Q2NUG0q3TRAsAu4CYQmrV5gnYWpPmffJbB3C C4pwQSOOWvKHQAPdITFPmfPP2vEgV/W4914ATmIIrQCwaUGSH0320JX58GX+YXkiT2oT VvmtaCEVtQnR5r/QYsQBo40n9VZ8UA7mXUXCI0xWGgz13jhQRDNCiKLf68ztPYqv/fYj bEQZpwRXtyFeLcxFLcC7QLtChgN03srERkN+ajfueYb9VW1BxNQBx1kSIa0dCaiee1Y2 gHsZFyqmgO14n1+aX2WKYP4xrQK6xFRxknEkDsnTSe4rZv54jv3Xft05/ANocb7OhLnp aK8w== X-Gm-Message-State: ABy/qLZK2wzYwfZAOUdNjJ8lkqRcOVenCmIEWd9WLUskekISFYJ9GAQ3 BYd0MY5GrB7BnYMzZ9VHLLs= X-Received: by 2002:a05:651c:cf:b0:2b9:b067:9559 with SMTP id 15-20020a05651c00cf00b002b9b0679559mr3382679ljr.23.1690927766923; Tue, 01 Aug 2023 15:09:26 -0700 (PDT) Received: from localhost.localdomain ([77.222.27.96]) by smtp.gmail.com with ESMTPSA id y18-20020a2e95d2000000b002b9ea00a7bbsm1391013ljh.60.2023.08.01.15.09.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Aug 2023 15:09:26 -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, dsahern@gmail.com, jbrouer@redhat.com, john.fastabend@gmail.com, linux-kernel@vger.kernel.org Cc: linux-kernel-mentees@lists.linuxfoundation.org, syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com, Andrew Kanner Subject: [PATCH v4 2/2] net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail() Date: Wed, 2 Aug 2023 01:07:13 +0300 Message-Id: <20230801220710.464-2-andrew.kanner@gmail.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20230801220710.464-1-andrew.kanner@gmail.com> References: <20230801220710.464-1-andrew.kanner@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=1.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.6 X-Spam-Level: * X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773075845129460783 X-GMAIL-MSGID: 1773075845129460783 Syzkaller reported the following issue: ======================================= Too BIG xdp->frame_sz = 131072 WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121 ____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline] WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121 bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103 ... Call Trace: bpf_prog_4add87e5301a4105+0x1a/0x1c __bpf_prog_run include/linux/filter.h:600 [inline] bpf_prog_run_xdp include/linux/filter.h:775 [inline] bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721 netif_receive_generic_xdp net/core/dev.c:4807 [inline] do_xdp_generic+0x35c/0x770 net/core/dev.c:4866 tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919 tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043 call_write_iter include/linux/fs.h:1871 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x650/0xe40 fs/read_write.c:584 ksys_write+0x12f/0x250 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87 ("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper Dangaard Brouer noted that after introducing the xdp_init_buff() which all XDP driver use - it's safe to remove this check. The original intend was to catch cases where XDP drivers have not been updated to use xdp.frame_sz, but that is not longer a concern (since xdp_init_buff). Running the initial syzkaller repro it was discovered that the contiguous physical memory allocation is used for both xdp paths in tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also stated by Jesper Dangaard Brouer that XDP can work on higher order pages, as long as this is contiguous physical memory (e.g. a page). Reported-and-tested-by: syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000774b9205f1d8a80d@google.com/T/ Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a Link: https://lore.kernel.org/all/20230725155403.796-1-andrew.kanner@gmail.com/T/ Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine") Signed-off-by: Andrew Kanner Acked-by: Jesper Dangaard Brouer Acked-by: Jason Wang --- net/core/filter.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 06ba0e56e369..28a59596987a 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4116,12 +4116,6 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset) if (unlikely(data_end > data_hard_end)) return -EINVAL; - /* ALL drivers MUST init xdp->frame_sz, chicken check below */ - if (unlikely(xdp->frame_sz > PAGE_SIZE)) { - WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz); - return -EINVAL; - } - if (unlikely(data_end < xdp->data + ETH_HLEN)) return -EINVAL;