From: John Fastabend <john.fastabend@xxxxxxxxx> commit d2db08c7a14e0b5eed6132baf258b80622e041a9 upstream. 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@xxxxxxxxx> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Link: https://lore.kernel.org/bpf/158560423908.10843.11783152347709008373.stgit@john-Precision-5820-Tower Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c | 5 ++ tools/testing/selftests/bpf/progs/test_get_stack_rawtp_err.c | 26 +++++++++++ 2 files changed, 31 insertions(+) --- 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 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; --- /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";
