Re: [PATCH] perf probe: convert_name_to_addr() allocated the wrongsize buffers for names

From: Masami Hiramatsu
Date: Wed Oct 17 2012 - 23:10:47 EST


(2012/10/18 10:20), Namhyung Kim wrote:
> Hi,
>
> On Wed, 17 Oct 2012 20:06:54 +0900, Masami Hiramatsu wrote:
>> (2012/10/17 17:28), Hyeoncheol Lee wrote:
>>> The function allocated wrong size buffers for names
>>>
>>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
>>> Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
>>> Signed-off-by: Hyeoncheol Lee <hyc.lee@xxxxxxxxx>
>>> ---
>>> tools/perf/util/probe-event.c | 11 +++++++----
>>> 1 file changed, 7 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
>>> index 49a256e..5cd7c42 100644
>>> --- a/tools/perf/util/probe-event.c
>>> +++ b/tools/perf/util/probe-event.c
>>> @@ -2273,6 +2273,8 @@ int show_available_funcs(const char *target, struct strfilter *_filter,
>>> return available_user_funcs(target);
>>> }
>>>
>>
>> Please add a comment like below on the code.
>>
>> /*
>> * sizeof(type) * 2 returns the maximum length of hexadecimal number
>> * of type, because each half byte is encoding in one hex character.
>> * Another 3 bytes are for "0x" and null character.
>> */
>>
>> Others are OK for me :)
>>
>> Thanks!
>>
>>> +#define MAX_ADDRNAME_LEN (3 + sizeof(unsigned long long) * 2)
>>> +
>>> /*
>>> * uprobe_events only accepts address:
>>> * Convert function and any offset to address
>>> @@ -2332,7 +2334,7 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)
>>> if (!pev->group) {
>>> char *ptr1, *ptr2, *exec_copy;
>>>
>>> - pev->group = zalloc(sizeof(char *) * 64);
>>> + pev->group = zalloc(sizeof(char) * 64);
>
> I guess we don't need this 'sizeof(char)' part?

Indeed, we don't need it from the viewpoint of C.
However I'd like to keep that, because it gives us a hint that
this buffer is used for string.

Thank you,

>
>
>>> exec_copy = strdup(exec);
>>> if (!exec_copy) {
>>> ret = -ENOMEM;
>>> @@ -2352,14 +2354,15 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)
>>> free(exec_copy);
>>> }
>>> free(pp->function);
>>> - pp->function = zalloc(sizeof(char *) * MAX_PROBE_ARGS);
>>> + pp->function = zalloc(sizeof(char) * MAX_ADDRNAME_LEN);
>
> Ditto.
>
> Thanks,
> Namhyung
>
>
>>> if (!pp->function) {
>>> ret = -ENOMEM;
>>> pr_warning("Failed to allocate memory by zalloc.\n");
>>> goto out;
>>> }
>>> - e_snprintf(pp->function, MAX_PROBE_ARGS, "0x%llx", vaddr);
>>> - ret = 0;
>>> + ret = e_snprintf(pp->function, MAX_ADDRNAME_LEN, "0x%llx", vaddr);
>>> + if (ret > 0)
>>> + ret = 0;
>>>
>>> out:
>>> if (map) {
>>>


--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx


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