On 10/11/2022 9:34 AM, Andrii Nakryiko wrote:
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?
Fine, but since free(NULL) works perfectly, will call free(name) unconditionally, and also initialize name to NULL, and call free(name) before sscanf.
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.
