From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-178.mta1.migadu.com [95.215.58.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A4E737475C for ; Mon, 24 Aug 2026 03:07:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787540879; cv=none; b=TTLYWut3XLEzEbS85uaqHr4Oi4o2bpe3q1FMMgLnNbkxTzF9l4gKJwLqb/j7bzDl64yULFXeyig20s6Nea2QlbOyOpP7EJ1AigghP8octToPnMF1efmWT7+tvzhcXHtdgrKT6jBm5lHnEFoOrhfw9h4KI85ibJJ3X4pqJe1+zio= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787540879; c=relaxed/simple; bh=l7q9NfVO33RZqDNAKsacw9ostqtqL107XpOn/D3Gino=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FnKZIiECIN43YayHxbwV1CCAhl5jepO1JQKqnQPlUzKuSVK9QsJ7+e6vCDBIXBHGsn6b+y+w6T0DUt/hSvKXrmzzWYw5Bju4GsrxCsd6PIIut9fBLJEsNE9U+iXuRlwph6EqBBxJrR7nhfSC/0dT0UBlClPG9rDFwa4r7q+s/mo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=IOGDx5Ub; arc=none smtp.client-ip=95.215.58.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="IOGDx5Ub" X-Envelope-To: linux-kselftest@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=l7q9NfVO33RZqDNAKsacw9ostqtqL107XpOn/D3Gino=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787540875; v=1; x=1788145675; b=IOGDx5UbkUc1UuEiDnbbKjG+65tX+P+a0Xp0/9CfDU3XUO5ioPCqS3G6gb/dxsWMTPb9Dekw DCV3LC8/wtaP995l4mMMQMYLcVAW96FqMxJaGwdYZUGFrFU4i6+IDEGgGF68LNwMGdQZkNPsbj5 B3QXjjeeFPEF/oU6GfnnUs14= X-Envelope-To: linux-kselftest@vger.kernel.org Received: from localhost.localdomain (147.136.157.0) by smtp.migadu.com with ESMTPS id ab67b601b70d2fa5; Mon, 24 Aug 2026 03:07:54 +0000 X-Mizu-Trace-ID: ab67b601b70d2fa5 X-Migadu-Flow: FLOW_OUT From: Jiayuan Chen To: bpf@vger.kernel.org, netdev@vger.kernel.org Cc: Jiayuan Chen , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Simon Horman , Martin KaFai Lau , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Shuah Khan , Kuniyuki Iwashima , Hangbin Liu , Krishna Kumar , Martin Karsten , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Lorenzo Bianconi , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf v2 2/2] selftests/bpf: add xdp_shrink_frags Date: Mon, 24 Aug 2026 11:06:44 +0800 Message-ID: <20260824030705.266049-2-jiayuan.chen@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260824030705.266049-1-jiayuan.chen@linux.dev> References: <20260824030257.263179-1-jiayuan.chen@linux.dev> <20260824030705.266049-1-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a test that attaches an xdp.frags program which shrinks a whole frag away, so bpf_xdp_shrink_data() frees a page_pool frag. test_tun triggers the page-type mismatch on the generic XDP path. test_veth triggers the same mismatch on the veth path. Both reproduce "Bad page state ... page_pool leak" on a buggy kernel. Signed-off-by: Jiayuan Chen --- .../bpf/prog_tests/xdp_shrink_frags.c | 163 ++++++++++++++++++ .../selftests/bpf/progs/xdp_shrink_frags.c | 23 +++ 2 files changed, 186 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_shrink_frags.c create mode 100644 tools/testing/selftests/bpf/progs/xdp_shrink_frags.c diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_shrink_frags.c b/tools/testing/selftests/bpf/prog_tests/xdp_shrink_frags.c new file mode 100644 index 000000000000..f3d8a84a6dc9 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/xdp_shrink_frags.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include "xdp_shrink_frags.skel.h" + +/* + * A generic-XDP program that shrinks into the frags frees a page_pool frag. + * skb-backed XDP first cow's the nonlinear skb into page_pool memory + * (skb_cow_data_for_xdp() for generic XDP, skb_pp_cow_data() for veth), but + * the shared rxq is registered as MEM_TYPE_PAGE_SHARED, so a buggy kernel + * frees the frag with page_frag_free() -> "Bad page state ... page_pool leak". + */ + +#define TAP_NAME "xdp_shrink0" +#define TAP_NETNS "xdp_shrink_tap" + +#define VETH_LOCAL "xdp_shrinkA" +#define VETH_PEER "xdp_shrinkB" +#define VETH_NETNS "xdp_shrink_veth" +#define VETH_LOCAL_IP "10.9.9.1" +#define VETH_PEER_IP "10.9.9.2" + +static int create_tap_napi_frags(const char *ifname) +{ + struct ifreq ifr = { + .ifr_flags = IFF_TAP | IFF_NO_PI | IFF_NAPI | IFF_NAPI_FRAGS, + }; + int fd, err; + + strscpy(ifr.ifr_name, ifname); + + fd = open("/dev/net/tun", O_RDWR); + if (fd < 0) + return -1; + + err = ioctl(fd, TUNSETIFF, &ifr); + if (err) { + close(fd); + return -1; + } + + return fd; +} + +/* + * Similar to flow_dissector.c: writev() an IFF_NAPI_FRAGS tap to build a + * nonlinear skb (sized for 4K pages, like xdp_adjust_tail.c) that tun runs + * through do_xdp_generic(). + */ +static void test_tun(struct xdp_shrink_frags *skel) +{ + __u8 head[74], frag1[2048], frag2[2048]; + struct ethhdr *eth = (void *)head; + int tap_fd = -1, ifindex, err; + struct netns_obj *ns = NULL; + struct iovec iov[3]; + ssize_t n; + + ns = netns_new(TAP_NETNS, true); + if (!ASSERT_OK_PTR(ns, "netns_new")) + return; + + tap_fd = create_tap_napi_frags(TAP_NAME); + if (!ASSERT_GE(tap_fd, 0, "create_tap")) + goto out; + + SYS(out, "ip link set dev " TAP_NAME " up"); + + ifindex = if_nametoindex(TAP_NAME); + if (!ASSERT_GT(ifindex, 0, "if_nametoindex")) + goto out; + + skel->bss->shrink_ran = 0; + + err = bpf_xdp_attach(ifindex, bpf_program__fd(skel->progs.xdp_shrink), + 0, NULL); + if (!ASSERT_OK(err, "bpf_xdp_attach")) + goto out; + + memset(head, 0, sizeof(head)); + memset(frag1, 0x41, sizeof(frag1)); + memset(frag2, 0x42, sizeof(frag2)); + eth->h_proto = htons(ETH_P_IP); + + iov[0].iov_base = head; iov[0].iov_len = sizeof(head); + iov[1].iov_base = frag1; iov[1].iov_len = sizeof(frag1); + iov[2].iov_base = frag2; iov[2].iov_len = sizeof(frag2); + + n = writev(tap_fd, iov, ARRAY_SIZE(iov)); + ASSERT_EQ(n, sizeof(head) + sizeof(frag1) + sizeof(frag2), "writev"); + + usleep(100 * 1000); + ASSERT_GT(skel->bss->shrink_ran, 0, "xdp_prog_ran"); + + bpf_xdp_detach(ifindex, 0, NULL); +out: + if (tap_fd >= 0) + close(tap_fd); + netns_free(ns); +} + +/* + * A large ping builds a nonlinear skb that veth cow's into its page_pool + * (sized for 4K pages, like xdp_adjust_tail.c) before running the program. + */ +static void test_veth(struct xdp_shrink_frags *skel) +{ + int ifindex, err; + + SYS(out, "ip netns add " VETH_NETNS); + SYS(out_ns, "ip link add %s mtu 8000 type veth peer name %s mtu 8000", + VETH_LOCAL, VETH_PEER); + SYS(out_link, "ip link set " VETH_PEER " netns " VETH_NETNS); + SYS(out_link, "ip addr add " VETH_LOCAL_IP "/24 dev " VETH_LOCAL); + SYS(out_link, "ip link set " VETH_LOCAL " up"); + SYS(out_link, "ip -n " VETH_NETNS " addr add " VETH_PEER_IP "/24 dev " VETH_PEER); + SYS(out_link, "ip -n " VETH_NETNS " link set " VETH_PEER " up"); + + ifindex = if_nametoindex(VETH_LOCAL); + if (!ASSERT_GT(ifindex, 0, "if_nametoindex")) + goto out_link; + + skel->bss->shrink_ran = 0; + + err = bpf_xdp_attach(ifindex, bpf_program__fd(skel->progs.xdp_shrink), + 0, NULL); + if (!ASSERT_OK(err, "bpf_xdp_attach")) + goto out_link; + + SYS_NOFAIL("ip netns exec " VETH_NETNS + " ping -q -s 5000 -c 3 -W 1 " VETH_LOCAL_IP); + + ASSERT_GT(skel->bss->shrink_ran, 0, "xdp_prog_ran"); + + bpf_xdp_detach(ifindex, 0, NULL); +out_link: + SYS_NOFAIL("ip link del " VETH_LOCAL); +out_ns: + SYS_NOFAIL("ip netns del " VETH_NETNS); +out: + return; +} + +void test_xdp_shrink_frags(void) +{ + struct xdp_shrink_frags *skel; + + skel = xdp_shrink_frags__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open_load")) + return; + + if (test__start_subtest("tun")) + test_tun(skel); + if (test__start_subtest("veth")) + test_veth(skel); + + xdp_shrink_frags__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/xdp_shrink_frags.c b/tools/testing/selftests/bpf/progs/xdp_shrink_frags.c new file mode 100644 index 000000000000..62e3791ac81d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/xdp_shrink_frags.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "vmlinux.h" +#include + +int shrink_ran; + +SEC("xdp.frags") +int xdp_shrink(struct xdp_md *ctx) +{ + /* + * The program is loaded with BPF_F_XDP_HAS_FRAGS (xdp.frags), so a + * nonlinear skb entering generic XDP is cow'd into page_pool memory + * before we run. Shrinking the tail far enough releases at least one + * whole frag, which must be returned to its page_pool. Count only a + * successful shrink so a too-small frame (e.g. ARP) does not satisfy + * the test. + */ + if (bpf_xdp_adjust_tail(ctx, -3000) == 0) + __sync_fetch_and_add(&shrink_ran, 1); + return XDP_PASS; +} + +char _license[] SEC("license") = "GPL"; -- 2.43.0