From patchwork Mon Oct 2 22:29:40 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Kanner X-Patchwork-Id: 13406601 X-Patchwork-Delegate: bpf@iogearbox.net 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 33CAF382; Mon, 2 Oct 2023 22:31:50 +0000 (UTC) Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E255591; Mon, 2 Oct 2023 15:31:47 -0700 (PDT) Received: by mail-lj1-x243.google.com with SMTP id 38308e7fff4ca-2c00e1d4c08so2704591fa.3; Mon, 02 Oct 2023 15:31:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696285906; x=1696890706; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=iZ4SCtr/9Ft8mS+V0BNVYtsyfhk4Y7ExsowxzrXeKBE=; b=JmTjjquVy3zaYTwmj9jfpuRLdW9NuuzWJAu4xLUy9imQUudOumRvaFgNEoFTItHYDh nISsmueDItWViU1u4O87vT7lYzofVwX2S7MhNQVqALXESaHn3Z6Z/bU+BSmPNJiSzL7n qcq6enzRBQKSyQoYg1eZf/KxCQsylNSBnQ5qU0/i8x7LxZ2q8uLimUBiF9NYvhORbNt+ ttaMpKnTUoj0rdNkTnUJcU4xpqtJfKh44dysFKDqNXnvWEtiKcW4fEv45GFQSRvpd1+B CKuyxTpOY95BCxG60V0OWhNytumUSUgP7YvBQy8CW9XwU1moFkKdyjYi/V35qJMuFr66 0GrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696285906; x=1696890706; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=iZ4SCtr/9Ft8mS+V0BNVYtsyfhk4Y7ExsowxzrXeKBE=; b=ERnAGR+9kt+o4B3cqhoB3wrVS3moKZxdGan+DUE0iMVDYTioa2KYU/i0zv/Xhc1wUd m3Gti4hLXOBq9Ifh7NaD73+oFMArPxfQnB0vuittCCa2Rnzgl2HEwPoa+JQ+yB9rJCjV lDllT3aSyoqJSe2Fs5x/YrdW4nEMmLo5sVYh8xx/fnFwuZnlOSAH7nbMauHVbTc4FJ0F 7qt9knTCYajo42xIEwYCKxiGl3qDGXVEeNboyCauupssUmDd8I3ZuQUp/W+2yf7swaFS T2GRtj+29H/cWY7CvYYZjjj73fJuX9DQpIbMzhQOAN7lkRqSvhjaL2al+qPsrbD1zDwn xuMg== X-Gm-Message-State: AOJu0Yzf2WjSGJBWFBdYyLkbTmgvQJXMw00jdzwuYB33qtcPls/bk3x5 iU9ZaYmV+eksul1zyGZjBao= X-Google-Smtp-Source: AGHT+IFaCQPJjfeaLO3tHZxSeqKnLvLg9cAsOZG2hZ+Nt8TEFFFBRge3VNTurmBZC9EWyG7/QMIyAQ== X-Received: by 2002:a2e:8505:0:b0:2bc:b9c7:7ba3 with SMTP id j5-20020a2e8505000000b002bcb9c77ba3mr10509789lji.12.1696285905850; Mon, 02 Oct 2023 15:31:45 -0700 (PDT) Received: from localhost.localdomain ([77.222.24.78]) by smtp.gmail.com with ESMTPSA id j3-20020a2eb703000000b002c0414c3b6csm5451574ljo.121.2023.10.02.15.31.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 15:31:45 -0700 (PDT) From: Andrew Kanner To: bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, aleksander.lobakin@intel.com, xuanzhuo@linux.alibaba.com, ast@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, daniel@iogearbox.net Cc: linux-kernel-mentees@lists.linuxfoundation.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+fae676d3cf469331fc89@syzkaller.appspotmail.com, Andrew Kanner Subject: [PATCH net-next v2] net/xdp: fix zero-size allocation warning in xskq_create() Date: Tue, 3 Oct 2023 01:29:40 +0300 Message-Id: <20231002222939.1519-1-andrew.kanner@gmail.com> X-Mailer: git-send-email 2.39.3 Precedence: bulk X-Mailing-List: bpf@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_BLOCKED,SPF_HELO_NONE,SPF_PASS 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 Syzkaller reported the following issue: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 2807 at mm/vmalloc.c:3247 __vmalloc_node_range (mm/vmalloc.c:3361) Modules linked in: CPU: 0 PID: 2807 Comm: repro Not tainted 6.6.0-rc2+ #12 Hardware name: Generic DT based system unwind_backtrace from show_stack (arch/arm/kernel/traps.c:258) show_stack from dump_stack_lvl (lib/dump_stack.c:107 (discriminator 1)) dump_stack_lvl from __warn (kernel/panic.c:633 kernel/panic.c:680) __warn from warn_slowpath_fmt (./include/linux/context_tracking.h:153 kernel/panic.c:700) warn_slowpath_fmt from __vmalloc_node_range (mm/vmalloc.c:3361 (discriminator 3)) __vmalloc_node_range from vmalloc_user (mm/vmalloc.c:3478) vmalloc_user from xskq_create (net/xdp/xsk_queue.c:40) xskq_create from xsk_setsockopt (net/xdp/xsk.c:953 net/xdp/xsk.c:1286) xsk_setsockopt from __sys_setsockopt (net/socket.c:2308) __sys_setsockopt from ret_fast_syscall (arch/arm/kernel/entry-common.S:68) xskq_get_ring_size() uses struct_size() macro to safely calculate the size of struct xsk_queue and q->nentries of desc members. But the syzkaller repro was able to set q->nentries with the value initially taken from copy_from_sockptr() high enough to return SIZE_MAX by struct_size(). The next PAGE_ALIGN(size) is such case will overflow the size_t value and set it to 0. This will trigger WARN_ON_ONCE in vmalloc_user() -> __vmalloc_node_range(). The issue is reproducible on 32-bit arm kernel. Reported-and-tested-by: syzbot+fae676d3cf469331fc89@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000c84b4705fb31741e@google.com/T/ Link: https://syzkaller.appspot.com/bug?extid=fae676d3cf469331fc89 Fixes: 9f78bf330a66 ("xsk: support use vaddr as ring") Signed-off-by: Andrew Kanner Reviewed-by: Alexander Lobakin Reported-by: syzbot+b132693e925cbbd89e26@syzkaller.appspotmail.com --- Notes (akanner): v2: - use unlikely() optimization for the case with SIZE_MAX return from struct_size(), suggested by Alexander Lobakin - cc-ed 4 more maintainers, mentioned by cc_maintainers patchwork test v1: https://lore.kernel.org/all/20230928204440.543-1-andrew.kanner@gmail.com/T/ - RFC notes: It was found that net/xdp/xsk.c:xsk_setsockopt() uses copy_from_sockptr() to get the number of entries (int) for cases with XDP_RX_RING / XDP_TX_RING and XDP_UMEM_FILL_RING / XDP_UMEM_COMPLETION_RING. Next in xsk_init_queue() there're 2 sanity checks (entries == 0) and (!is_power_of_2(entries)) for which -EINVAL will be returned. After that net/xdp/xsk_queue.c:xskq_create() will calculate the size multipling the number of entries (int) with the size of u64, at least. I wonder if there should be the upper bound (e.g. the 3rd sanity check inside xsk_init_queue()). It seems that without the upper limit it's quiet easy to overflow the allocated size (SIZE_MAX), especially for 32-bit architectures, for example arm nodes which were used by the syzkaller. In this patch I added a naive check for SIZE_MAX which helped to skip zero-size allocation after overflow, but maybe it's not quite right. Please, suggest if you have any thoughts about the appropriate limit for the size of these xdp rings. PS: the initial number of entries is 0x20000000 in syzkaller repro: syscall(__NR_setsockopt, (intptr_t)r[0], 0x11b, 3, 0x20000040, 0x20); Link: https://syzkaller.appspot.com/text?tag=ReproC&x=10910f18280000 net/xdp/xsk_queue.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c index f8905400ee07..b03d1bfb6978 100644 --- a/net/xdp/xsk_queue.c +++ b/net/xdp/xsk_queue.c @@ -34,6 +34,9 @@ struct xsk_queue *xskq_create(u32 nentries, bool umem_queue) q->ring_mask = nentries - 1; size = xskq_get_ring_size(q, umem_queue); + if (unlikely(size == SIZE_MAX)) + return NULL; + size = PAGE_ALIGN(size); q->ring = vmalloc_user(size);