Commit d2db08c7 authored by John Fastabend's avatar John Fastabend Committed by Alexei Starovoitov
Browse files

bpf: Test_progs, add test to catch retval refine error handling 



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: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158560423908.10843.11783152347709008373.stgit@john-Precision-5820-Tower
parent fa123ac0

tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c

+5 −0
Original line number Diff line number Diff line
@@ -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;

tools/testing/selftests/bpf/progs/test_get_stack_rawtp_err.c

0 → 100644
+26 −0
Original line number Diff line number Diff line 
// 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";

CRA Git | Maintained and supported by SUSTech CRA and CCSE