On Mon, Oct 10, 2022 at 7:08 AM Xu Kuohai <xukuohai@xxxxxxxxxx> wrote:
>
> The get_syms() function in kprobe_multi_test.c does not free the string
> memory allocated by sscanf correctly. Fix it.
>
> Fixes: 5b6c7e5c4434 ("selftests/bpf: Add attach bench test")
> Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> .../bpf/prog_tests/kprobe_multi_test.c | 17 ++++++++---------
> 1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> index d457a55ff408..07dd2c5b7f98 100644
> --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> @@ -360,15 +360,14 @@ static int get_syms(char ***symsp, size_t *cntp)
> * to them. Filter out the current culprits - arch_cpu_idle
> * and rcu_* functions.
> */
> - if (!strcmp(name, "arch_cpu_idle"))
> - continue;
> - if (!strncmp(name, "rcu_", 4))
> - continue;
> - if (!strcmp(name, "bpf_dispatcher_xdp_func"))
> - continue;
> - if (!strncmp(name, "__ftrace_invalid_address__",
> - sizeof("__ftrace_invalid_address__") - 1))
> + if (!strcmp(name, "arch_cpu_idle") ||
> + !strncmp(name, "rcu_", 4) ||
> + !strcmp(name, "bpf_dispatcher_xdp_func") ||
> + !strncmp(name, "__ftrace_invalid_address__",
> + sizeof("__ftrace_invalid_address__") - 1)) {
> + free(name);
> continue;
> + }
it seems cleaner if we add if (name) free(name) under error: goto
label. And in the success case when we assign name to syms[cnt] we can
reset name to NULL to avoid double-free. WDYT?
> err = hashmap__add(map, name, NULL);
> if (err) {
> free(name);
> @@ -394,7 +393,7 @@ static int get_syms(char ***symsp, size_t *cntp)
> hashmap__free(map);
> if (err) {
> for (i = 0; i < cnt; i++)
> - free(syms[cnt]);
> + free(syms[i]);
> free(syms);
> }
> return err;
> --
> 2.30.2
>
