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From: John Fastabend <john.fastabend@gmail.com>
To: ecree@solarflare.com, yhs@fb.com, alexei.starovoitov@gmail.com,
	daniel@iogearbox.net
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, john.fastabend@gmail.com
Subject: [bpf-next PATCH 06/10] bpf: test_progs, add test to catch retval refine error handling
Date: Tue, 24 Mar 2020 10:39:36 -0700
Message-ID: <158507157618.15666.3720338936586861726.stgit@john-Precision-5820-Tower> (raw)
In-Reply-To: <158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower>

Before this series the verifier would clamp return bounds of
bpf_get_stack() to [0, X] and this led the verifier to believe
that a JMP_JSLT 0 would be false and so would prune that path.

The result is anything hidden behind that JSLT would be unverified.
Add a test to catch this case by hiding an goto pc-1 behind the
check which will cause an infinite loop if not rejected.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---
 .../selftests/bpf/prog_tests/get_stack_raw_tp.c    |    5 ++++
 .../selftests/bpf/progs/test_get_stack_rawtp_err.c |   26 ++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/test_get_stack_rawtp_err.c

diff --git a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
index eba9a97..9257222 100644
--- a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
+++ b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
@@ -82,6 +82,7 @@ static void get_stack_print_output(void *ctx, int cpu, void *data, __u32 size)
 void test_get_stack_raw_tp(void)
 {
 	const char *file = "./test_get_stack_rawtp.o";
+	const char *file_err = "./test_get_stack_rawtp_err.o";
 	const char *prog_name = "raw_tracepoint/sys_enter";
 	int i, err, prog_fd, exp_cnt = MAX_CNT_RAWTP;
 	struct perf_buffer_opts pb_opts = {};
@@ -93,6 +94,10 @@ void test_get_stack_raw_tp(void)
 	struct bpf_map *map;
 	cpu_set_t cpu_set;
 
+	err = bpf_prog_load(file_err, BPF_PROG_TYPE_RAW_TRACEPOINT, &obj, &prog_fd);
+	if (CHECK(err >= 0, "prog_load raw tp", "err %d errno %d\n", err, errno))
+		return;
+
 	err = bpf_prog_load(file, BPF_PROG_TYPE_RAW_TRACEPOINT, &obj, &prog_fd);
 	if (CHECK(err, "prog_load raw tp", "err %d errno %d\n", err, errno))
 		return;
diff --git a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp_err.c b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp_err.c
new file mode 100644
index 0000000..8941a41
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp_err.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+#define MAX_STACK_RAWTP 10
+
+SEC("raw_tracepoint/sys_enter")
+int bpf_prog2(void *ctx)
+{
+	__u64 stack[MAX_STACK_RAWTP];
+	int error;
+
+	/* set all the flags which should return -EINVAL */
+	error = bpf_get_stack(ctx, stack, 0, -1);
+	if (error < 0)
+		goto loop;
+
+	return error;
+loop:
+	while (1) {
+		error++;
+	}
+}
+
+char _license[] SEC("license") = "GPL";


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 17:37 [bpf-next PATCH 00/10] ALU32 bounds tracking support John Fastabend
2020-03-24 17:37 ` [bpf-next PATCH 01/10] bpf: verifier, do_refine_retval_range may clamp umin to 0 incorrectly John Fastabend
2020-03-24 17:38 ` [bpf-next PATCH 02/10] bpf: verifer, refactor adjust_scalar_min_max_vals John Fastabend
2020-03-26  6:10   ` Alexei Starovoitov
2020-03-24 17:38 ` [bpf-next PATCH 03/10] bpf: verifer, adjust_scalar_min_max_vals to always call update_reg_bounds() John Fastabend
2020-03-24 17:38 ` [bpf-next PATCH 04/10] bpf: verifier, do explicit ALU32 bounds tracking John Fastabend
2020-03-26  6:20   ` Alexei Starovoitov
2020-03-26 15:18     ` John Fastabend
2020-03-24 17:39 ` [bpf-next PATCH 05/10] bpf: verifier, return value is an int in do_refine_retval_range John Fastabend
2020-03-26  6:23   ` Alexei Starovoitov
2020-03-26 15:52     ` John Fastabend
2020-03-24 17:39 ` John Fastabend [this message]
2020-03-24 17:39 ` [bpf-next PATCH 07/10] bpf: test_verifier, bpf_get_stack return value add <0 John Fastabend
2020-03-26  6:33   ` Alexei Starovoitov
2020-03-26 15:48     ` John Fastabend
2020-03-24 17:40 ` [bpf-next PATCH 08/10] bpf: test_verifier, #70 error message updates for 32-bit right shift John Fastabend
2020-03-24 17:40 ` [bpf-next PATCH 09/10] bpf: test_verifier, #65 error message updates for trunc of boundary-cross John Fastabend
2020-03-24 17:40 ` [bpf-next PATCH 10/10] bpf: test_verifier, add alu32 bounds tracking tests John Fastabend
2020-03-26  6:34   ` Alexei Starovoitov

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