From: Amery Hung <ameryhung@gmail.com>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com,
andrii@kernel.org, daniel@iogearbox.net, memxor@gmail.com,
martin.lau@kernel.org, ameryhung@gmail.com, kernel-team@meta.com
Subject: [RFC PATCH bpf-next v2 09/11] selftests/bpf: Test using dynptr after freeing the underlying object
Date: Fri, 6 Mar 2026 22:44:37 -0800 [thread overview]
Message-ID: <20260307064439.3247440-10-ameryhung@gmail.com> (raw)
In-Reply-To: <20260307064439.3247440-1-ameryhung@gmail.com>
Make sure the verifier invalidates the dynptr and dynptr slice derived
from an skb after the skb is freed.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
.../selftests/bpf/prog_tests/bpf_qdisc.c | 36 ++++++++++
.../progs/bpf_qdisc_fail__invalid_dynptr.c | 62 +++++++++++++++++
...f_qdisc_fail__invalid_dynptr_cross_frame.c | 68 +++++++++++++++++++
.../bpf_qdisc_fail__invalid_dynptr_slice.c | 64 +++++++++++++++++
4 files changed, 230 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr.c
create mode 100644 tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_cross_frame.c
create mode 100644 tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_slice.c
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c b/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c
index 730357cd0c9a..ec5b346138c5 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c
@@ -8,6 +8,9 @@
#include "bpf_qdisc_fifo.skel.h"
#include "bpf_qdisc_fq.skel.h"
#include "bpf_qdisc_fail__incompl_ops.skel.h"
+#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"
#define LO_IFINDEX 1
@@ -156,6 +159,33 @@ static void test_incompl_ops(void)
bpf_qdisc_fail__incompl_ops__destroy(skel);
}
+static void test_invalid_dynptr(void)
+{
+ struct bpf_qdisc_fail__invalid_dynptr *skel;
+
+ skel = bpf_qdisc_fail__invalid_dynptr__open_and_load();
+ if (!ASSERT_ERR_PTR(skel, "bpf_qdisc_fail__invalid_dynptr__open_and_load"))
+ bpf_qdisc_fail__invalid_dynptr__destroy(skel);
+}
+
+static void test_invalid_dynptr_slice(void)
+{
+ struct bpf_qdisc_fail__invalid_dynptr_slice *skel;
+
+ skel = bpf_qdisc_fail__invalid_dynptr_slice__open_and_load();
+ if (!ASSERT_ERR_PTR(skel, "bpf_qdisc_fail__invalid_dynptr_slice__open_and_load"))
+ bpf_qdisc_fail__invalid_dynptr_slice__destroy(skel);
+}
+
+static void test_invalid_dynptr_cross_frame(void)
+{
+ struct bpf_qdisc_fail__invalid_dynptr_cross_frame *skel;
+
+ skel = bpf_qdisc_fail__invalid_dynptr_cross_frame__open_and_load();
+ if (!ASSERT_ERR_PTR(skel, "bpf_qdisc_fail__invalid_dynptr_cross_frame__open_and_load"))
+ bpf_qdisc_fail__invalid_dynptr_cross_frame__destroy(skel);
+}
+
static int get_default_qdisc(char *qdisc_name)
{
FILE *f;
@@ -223,6 +253,12 @@ void test_ns_bpf_qdisc(void)
test_qdisc_attach_to_non_root();
if (test__start_subtest("incompl_ops"))
test_incompl_ops();
+ if (test__start_subtest("invalid_dynptr"))
+ test_invalid_dynptr();
+ if (test__start_subtest("invalid_dynptr_slice"))
+ test_invalid_dynptr_slice();
+ if (test__start_subtest("invalid_dynptr_cross_frame"))
+ test_invalid_dynptr_cross_frame();
}
void serial_test_bpf_qdisc_default(void)
diff --git a/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr.c b/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr.c
new file mode 100644
index 000000000000..2e76470bc261
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include "bpf_experimental.h"
+#include "bpf_qdisc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+int proto;
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_enqueue, struct sk_buff *skb, struct Qdisc *sch,
+ struct bpf_sk_buff_ptr *to_free)
+{
+ struct bpf_dynptr ptr;
+ struct ethhdr *hdr;
+
+ bpf_dynptr_from_skb((struct __sk_buff *)skb, 0, &ptr);
+
+ bpf_qdisc_skb_drop(skb, to_free);
+
+ hdr = bpf_dynptr_slice(&ptr, 0, NULL, sizeof(*hdr));
+ if (!hdr)
+ return NET_XMIT_DROP;
+
+ proto = hdr->h_proto;
+
+ return NET_XMIT_DROP;
+}
+
+SEC("struct_ops")
+struct sk_buff *BPF_PROG(bpf_qdisc_test_dequeue, struct Qdisc *sch)
+{
+ return NULL;
+}
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_init, struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ return 0;
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_reset, struct Qdisc *sch)
+{
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_destroy, struct Qdisc *sch)
+{
+}
+
+SEC(".struct_ops")
+struct Qdisc_ops test = {
+ .enqueue = (void *)bpf_qdisc_test_enqueue,
+ .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",
+};
diff --git a/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_cross_frame.c b/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_cross_frame.c
new file mode 100644
index 000000000000..565dea13bde8
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_cross_frame.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include "bpf_experimental.h"
+#include "bpf_qdisc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+int proto;
+
+static __noinline int free_skb(struct sk_buff *skb)
+{
+ bpf_kfree_skb(skb);
+ return 0;
+}
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_enqueue, struct sk_buff *skb, struct Qdisc *sch,
+ struct bpf_sk_buff_ptr *to_free)
+{
+ struct bpf_dynptr ptr;
+ struct ethhdr *hdr;
+
+ bpf_dynptr_from_skb((struct __sk_buff *)skb, 0, &ptr);
+
+ hdr = bpf_dynptr_slice(&ptr, 0, NULL, sizeof(*hdr));
+ if (!hdr)
+ return NET_XMIT_DROP;
+
+ free_skb(skb);
+
+ proto = hdr->h_proto;
+
+ return NET_XMIT_DROP;
+}
+
+SEC("struct_ops")
+struct sk_buff *BPF_PROG(bpf_qdisc_test_dequeue, struct Qdisc *sch)
+{
+ return NULL;
+}
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_init, struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ return 0;
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_reset, struct Qdisc *sch)
+{
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_destroy, struct Qdisc *sch)
+{
+}
+
+SEC(".struct_ops")
+struct Qdisc_ops test = {
+ .enqueue = (void *)bpf_qdisc_test_enqueue,
+ .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",
+};
diff --git a/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_slice.c b/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_slice.c
new file mode 100644
index 000000000000..95e8c070a37d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_qdisc_fail__invalid_dynptr_slice.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include "bpf_experimental.h"
+#include "bpf_qdisc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+int proto;
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_enqueue, struct sk_buff *skb, struct Qdisc *sch,
+ struct bpf_sk_buff_ptr *to_free)
+{
+ struct bpf_dynptr ptr;
+ struct ethhdr *hdr;
+
+ bpf_dynptr_from_skb((struct __sk_buff *)skb, 0, &ptr);
+
+ hdr = bpf_dynptr_slice(&ptr, 0, NULL, sizeof(*hdr));
+ if (!hdr) {
+ bpf_qdisc_skb_drop(skb, to_free);
+ return NET_XMIT_DROP;
+ }
+
+ bpf_qdisc_skb_drop(skb, to_free);
+
+ proto = hdr->h_proto;
+
+ return NET_XMIT_DROP;
+}
+
+SEC("struct_ops")
+struct sk_buff *BPF_PROG(bpf_qdisc_test_dequeue, struct Qdisc *sch)
+{
+ return NULL;
+}
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_init, struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ return 0;
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_reset, struct Qdisc *sch)
+{
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_destroy, struct Qdisc *sch)
+{
+}
+
+SEC(".struct_ops")
+struct Qdisc_ops test = {
+ .enqueue = (void *)bpf_qdisc_test_enqueue,
+ .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",
+};
--
2.47.3
next prev parent reply other threads:[~2026-03-07 6:44 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-07 6:44 [RFC PATCH bpf-next v2 00/11] Dynptr cleanup and bugfixes Amery Hung
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 01/11] bpf: Set kfunc dynptr arg type flag based on prototype Amery Hung
2026-03-11 14:47 ` Mykyta Yatsenko
2026-03-11 16:34 ` Amery Hung
2026-03-11 19:43 ` Andrii Nakryiko
2026-03-11 20:01 ` Amery Hung
2026-03-11 22:37 ` Andrii Nakryiko
2026-03-11 23:03 ` Amery Hung
2026-03-11 23:15 ` Andrii Nakryiko
2026-03-12 16:59 ` Amery Hung
2026-03-12 20:09 ` Andrii Nakryiko
2026-03-13 3:25 ` Alexei Starovoitov
2026-03-16 20:57 ` Eduard Zingerman
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 02/11] selftests/bpf: Test passing CONST_PTR_TO_DYNPTR to kfunc that may mutate dynptr Amery Hung
2026-03-11 15:26 ` Mykyta Yatsenko
2026-03-11 16:38 ` Amery Hung
2026-03-11 16:56 ` Amery Hung
2026-03-16 21:35 ` Eduard Zingerman
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 03/11] bpf: Unify dynptr handling in the verifier Amery Hung
2026-03-11 16:03 ` Mykyta Yatsenko
2026-03-11 17:23 ` Amery Hung
2026-03-11 22:22 ` Mykyta Yatsenko
2026-03-11 22:35 ` Amery Hung
2026-03-11 19:57 ` Andrii Nakryiko
2026-03-11 20:16 ` Amery Hung
2026-03-16 22:52 ` Eduard Zingerman
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 04/11] bpf: Assign reg->id when getting referenced kptr from ctx Amery Hung
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 05/11] bpf: Preserve reg->id of pointer objects after null-check Amery Hung
2026-03-11 21:55 ` Andrii Nakryiko
2026-03-11 22:26 ` Alexei Starovoitov
2026-03-11 22:29 ` Alexei Starovoitov
2026-03-11 23:46 ` Amery Hung
2026-03-17 18:49 ` Eduard Zingerman
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 06/11] bpf: Refactor object relationship tracking and fix dynptr UAF bug Amery Hung
2026-03-11 22:32 ` Andrii Nakryiko
2026-03-13 20:32 ` Amery Hung
2026-03-12 23:33 ` Mykyta Yatsenko
2026-03-13 20:33 ` Amery Hung
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 07/11] bpf: Remove redundant dynptr arg check for helper Amery Hung
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 08/11] selftests/bpf: Test creating dynptr from dynptr data and slice Amery Hung
2026-03-07 6:44 ` Amery Hung [this message]
2026-03-16 19:25 ` [RFC PATCH bpf-next v2 09/11] selftests/bpf: Test using dynptr after freeing the underlying object Eduard Zingerman
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 10/11] selftests/bpf: Test using slice after invalidating dynptr clone Amery Hung
2026-03-07 6:44 ` [RFC PATCH bpf-next v2 11/11] selftests/bpf: Test using file dynptr after the reference on file is dropped Amery Hung
2026-03-11 19:38 ` [RFC PATCH bpf-next v2 00/11] Dynptr cleanup and bugfixes Andrii Nakryiko
2026-03-13 20:49 ` Amery Hung
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260307064439.3247440-10-ameryhung@gmail.com \
--to=ameryhung@gmail.com \
--cc=alexei.starovoitov@gmail.com \
--cc=andrii@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kernel-team@meta.com \
--cc=martin.lau@kernel.org \
--cc=memxor@gmail.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox