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Tue, 21 Apr 2026 15:10:26 -0700 (PDT) Received: from localhost ([2a03:2880:ff:5b::]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b5fab30f29sm142158255ad.68.2026.04.21.15.10.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 15:10:26 -0700 (PDT) From: Amery Hung To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, memxor@gmail.com, martin.lau@kernel.org, mykyta.yatsenko5@gmail.com, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v3 8/9] selftests/bpf: Test using slice after invalidating dynptr clone Date: Tue, 21 Apr 2026 15:10:15 -0700 Message-ID: <20260421221016.2967924-9-ameryhung@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260421221016.2967924-1-ameryhung@gmail.com> References: <20260421221016.2967924-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The parent object of a cloned dynptr is skb not the original dynptr. Invalidate the original dynptr should not prevent the program from using the slice derived from the cloned dynptr. Signed-off-by: Amery Hung --- .../selftests/bpf/prog_tests/bpf_qdisc.c | 2 + ..._qdisc_dynptr_use_after_invalidate_clone.c | 75 +++++++++++++++++++ 2 files changed, 77 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/bpf_qdisc_dynptr_use_after_invalidate_clone.c diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c b/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c index 65277c8fc887..77f1c0550c9b 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c @@ -11,6 +11,7 @@ #include "bpf_qdisc_fail__invalid_dynptr.skel.h" #include "bpf_qdisc_fail__invalid_dynptr_slice.skel.h" #include "bpf_qdisc_fail__invalid_dynptr_cross_frame.skel.h" +#include "bpf_qdisc_dynptr_use_after_invalidate_clone.skel.h" #define LO_IFINDEX 1 @@ -229,6 +230,7 @@ void test_ns_bpf_qdisc(void) RUN_TESTS(bpf_qdisc_fail__invalid_dynptr); RUN_TESTS(bpf_qdisc_fail__invalid_dynptr_cross_frame); RUN_TESTS(bpf_qdisc_fail__invalid_dynptr_slice); + RUN_TESTS(bpf_qdisc_dynptr_use_after_invalidate_clone); } void serial_test_bpf_qdisc_default(void) diff --git a/tools/testing/selftests/bpf/progs/bpf_qdisc_dynptr_use_after_invalidate_clone.c b/tools/testing/selftests/bpf/progs/bpf_qdisc_dynptr_use_after_invalidate_clone.c new file mode 100644 index 000000000000..cca2accf081d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/bpf_qdisc_dynptr_use_after_invalidate_clone.c @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include "bpf_experimental.h" +#include "bpf_qdisc_common.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +int proto; + +SEC("struct_ops") +__success +int BPF_PROG(dynptr_use_after_invalidate_clone, struct sk_buff *skb, struct Qdisc *sch, + struct bpf_sk_buff_ptr *to_free) +{ + struct bpf_dynptr ptr, ptr_clone; + struct ethhdr *hdr; + + bpf_dynptr_from_skb((struct __sk_buff *)skb, 0, &ptr); + + bpf_dynptr_clone(&ptr, &ptr_clone); + + hdr = bpf_dynptr_slice(&ptr_clone, 0, NULL, sizeof(*hdr)); + if (!hdr) { + bpf_qdisc_skb_drop(skb, to_free); + return NET_XMIT_DROP; + } + + *(int *)&ptr = 0; + + proto = hdr->h_proto; + + bpf_qdisc_skb_drop(skb, to_free); + + return NET_XMIT_DROP; +} + +SEC("struct_ops") +__auxiliary +struct sk_buff *BPF_PROG(bpf_qdisc_test_dequeue, struct Qdisc *sch) +{ + return NULL; +} + +SEC("struct_ops") +__auxiliary +int BPF_PROG(bpf_qdisc_test_init, struct Qdisc *sch, struct nlattr *opt, + struct netlink_ext_ack *extack) +{ + return 0; +} + +SEC("struct_ops") +__auxiliary +void BPF_PROG(bpf_qdisc_test_reset, struct Qdisc *sch) +{ +} + +SEC("struct_ops") +__auxiliary +void BPF_PROG(bpf_qdisc_test_destroy, struct Qdisc *sch) +{ +} + +SEC(".struct_ops") +struct Qdisc_ops test = { + .enqueue = (void *)dynptr_use_after_invalidate_clone, + .dequeue = (void *)bpf_qdisc_test_dequeue, + .init = (void *)bpf_qdisc_test_init, + .reset = (void *)bpf_qdisc_test_reset, + .destroy = (void *)bpf_qdisc_test_destroy, + .id = "bpf_qdisc_test", +}; + -- 2.52.0