2020-06-24 01:38:46

by Gaurav Singh

Subject: [PATCH] [perf] lsdir_bid_tail_filter: fix index check

Check bounds before accessing d->d_name[].

Signed-off-by: Gaurav Singh <[email protected]>
---
tools/perf/util/build-id.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index c076fc7fe025..8c35cbe93f10 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -431,7 +431,7 @@ static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
struct dirent *d)
{
int i = 0;
- while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
+ while (i < SBUILD_ID_SIZE - 3 && isxdigit(d->d_name[i]))
i++;
return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
}
--
2.17.1

2020-06-24 12:51:50

by Jiri Olsa

Subject: Re: [PATCH] [perf] lsdir_bid_tail_filter: fix index check

On Tue, Jun 23, 2020 at 09:35:22PM -0400, Gaurav Singh wrote:
> Check bounds before accessing d->d_name[].
>
> Signed-off-by: Gaurav Singh <[email protected]>
> ---
> tools/perf/util/build-id.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index c076fc7fe025..8c35cbe93f10 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -431,7 +431,7 @@ static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
> struct dirent *d)
> {
> int i = 0;
> - while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
> + while (i < SBUILD_ID_SIZE - 3 && isxdigit(d->d_name[i]))

hum, I guess it looks better, but technicaly this is not a problem right?

isxdigit will return false on zero byte which is always present in d->d_name
so it will never get out of bounds

jirka

> i++;
> return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
> }
> --
> 2.17.1
>