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@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
---
.../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;
+ }
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;
--
2.30.2On Mon, Oct 10, 2022 at 7:08 AM Xu Kuohai <xukuohai@huawei.com> 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@huawei.com>
> Acked-by: Jiri Olsa <jolsa@kernel.org>
> ---
> .../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
>
On 10/11/2022 9:34 AM, Andrii Nakryiko wrote:
> On Mon, Oct 10, 2022 at 7:08 AM Xu Kuohai <xukuohai@huawei.com> 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@huawei.com>
>> Acked-by: Jiri Olsa <jolsa@kernel.org>
>> ---
>> .../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
>>
> .
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