From: Emil Tsalapatis <emil@etsalapatis.com>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, andrii@kernel.org, eddyz87@gmail.com,
memxor@gmail.com, daniel@iogearbox.net, netdev@vger.kernel.org,
Emil Tsalapatis <emil@etsalapatis.com>
Subject: [PATCH bpf 02/11] selftests/bpf: Test dynptr slices past end of skb
Date: Wed, 16 Sep 2026 05:08:20 +0000 [thread overview]
Message-ID: <20260916050830.8774-3-emil@etsalapatis.com> (raw)
In-Reply-To: <20260916050830.8774-1-emil@etsalapatis.com>
Add a selftest to ensure dynptr slices cannot include
past the end of the linear area of an skb.
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
.../testing/selftests/bpf/prog_tests/dynptr.c | 10 ++++++++++
.../selftests/bpf/progs/dynptr_success.c | 20 +++++++++++++++++++
2 files changed, 30 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index 5fda11590..439656036 100644
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -9,6 +9,7 @@
enum test_setup_type {
SETUP_SYSCALL_SLEEP,
SETUP_SKB_PROG,
+ SETUP_SKB_PROG_NONLINEAR,
SETUP_SKB_PROG_TP,
SETUP_XDP_PROG,
};
@@ -32,6 +33,7 @@ static struct {
{"test_ringbuf", SETUP_SYSCALL_SLEEP},
{"test_skb_readonly", SETUP_SKB_PROG},
{"test_dynptr_skb_data", SETUP_SKB_PROG},
+ {"test_dynptr_skb_slice_non_linear", SETUP_SKB_PROG_NONLINEAR},
{"test_dynptr_skb_meta_data", SETUP_SKB_PROG},
{"test_dynptr_skb_meta_flags", SETUP_SKB_PROG},
{"test_adjust", SETUP_SYSCALL_SLEEP},
@@ -94,7 +96,9 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
bpf_link__destroy(link);
break;
case SETUP_SKB_PROG:
+ case SETUP_SKB_PROG_NONLINEAR:
{
+ struct __sk_buff ctx = {};
int prog_fd;
char buf[64];
@@ -106,6 +110,12 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
.repeat = 1,
);
+ if (setup_type == SETUP_SKB_PROG_NONLINEAR) {
+ ctx.data_end = ETH_HLEN + sizeof(struct iphdr);
+ topts.ctx_in = &ctx;
+ topts.ctx_size_in = sizeof(ctx);
+ }
+
prog_fd = bpf_program__fd(prog);
if (!ASSERT_GE(prog_fd, 0, "prog_fd"))
goto cleanup;
diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
index e0745b6e4..b668ebd61 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_success.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
@@ -10,6 +10,7 @@
#include "errno.h"
#define PAGE_SIZE_64K 65536
+#define TEST_SKB_LINEAR_SIZE (sizeof(struct ethhdr) + sizeof(struct iphdr))
char _license[] SEC("license") = "GPL";
@@ -211,6 +212,25 @@ int test_dynptr_skb_data(struct __sk_buff *skb)
return 1;
}
+SEC("?tc")
+int test_dynptr_skb_slice_non_linear(struct __sk_buff *skb)
+{
+ struct bpf_dynptr ptr;
+ void *data;
+
+ if (bpf_dynptr_from_skb(skb, 0, &ptr)) {
+ err = 1;
+ return 1;
+ }
+
+ /* Ensure we cannot read past the end of the buffer. */
+ data = bpf_dynptr_slice(&ptr, TEST_SKB_LINEAR_SIZE + 1, NULL, 1);
+ if (data)
+ err = 2;
+
+ return 1;
+}
+
SEC("?tc")
int test_dynptr_skb_meta_data(struct __sk_buff *skb)
{
--
2.54.0
next prev parent reply other threads:[~2026-09-16 5:08 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-16 5:08 [PATCH bpf 00/11] skb/arena bugfixes Emil Tsalapatis
2026-09-16 5:08 ` [PATCH bpf 01/11] bpf: Fix bounds check for skb-backed dynptrs Emil Tsalapatis
2026-09-16 11:52 ` Jiayuan Chen
2026-09-16 23:08 ` Jakub Kicinski
2026-09-16 5:08 ` Emil Tsalapatis [this message]
2026-09-16 5:18 ` [PATCH bpf 02/11] selftests/bpf: Test dynptr slices past end of skb sashiko-bot
2026-09-16 5:08 ` [PATCH bpf 03/11] bpf: Fix bpf_sock context code generation Emil Tsalapatis
2026-09-16 12:21 ` Jiayuan Chen
2026-09-16 5:08 ` [PATCH bpf 04/11] selftests/bpf: Add selftests for rx_queue_mapping context access Emil Tsalapatis
2026-09-16 5:08 ` [PATCH bpf 05/11] bpf: Reject pkt arguments in mutating subprogs Emil Tsalapatis
2026-09-16 5:57 ` Amery Hung
2026-09-16 5:58 ` Amery Hung
2026-09-16 18:41 ` Emil Tsalapatis
2026-09-16 19:26 ` Amery Hung
2026-09-16 5:08 ` [PATCH bpf 06/11] selftests/bpf: Test rejection of pkt args to " Emil Tsalapatis
2026-09-16 5:08 ` [PATCH bpf 07/11] bpf: Prevent variable arena/non-arena register contents Emil Tsalapatis
2026-09-16 5:08 ` [PATCH bpf 08/11] selftests/bpf: Test for mixed arena/nonarena code paths Emil Tsalapatis
2026-09-16 5:17 ` sashiko-bot
2026-09-16 5:08 ` [PATCH bpf 09/11] bpf: Track whether dynptr type is known Emil Tsalapatis
2026-09-16 5:22 ` sashiko-bot
2026-09-16 18:41 ` Emil Tsalapatis
2026-09-16 5:08 ` [PATCH bpf 10/11] bpf: Track skb memory invalidation by packet-backed dynptrs Emil Tsalapatis
2026-09-16 5:08 ` [PATCH bpf 11/11] selftests/bpf: Test dynptr slice invalidation on skb clobber Emil Tsalapatis
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