* [PATCH] [perf] Fix null pointer deference in nest_epollfd
@ 2020-06-18 0:38 Gaurav Singh
2020-06-18 14:48 ` Namhyung Kim
0 siblings, 1 reply; 3+ messages in thread
From: Gaurav Singh @ 2020-06-18 0:38 UTC (permalink / raw)
To: gaurav1086, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Mark Rutland, Alexander Shishkin,
Jiri Olsa, Namhyung Kim, Tommi Rantala, Thomas Gleixner,
open list:PERFORMANCE EVENTS SUBSYSTEM
Add a NULL check for worker before dereferencing.
Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
---
tools/perf/bench/epoll-wait.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/perf/bench/epoll-wait.c b/tools/perf/bench/epoll-wait.c
index 75dca9773186..42983eb7f82e 100644
--- a/tools/perf/bench/epoll-wait.c
+++ b/tools/perf/bench/epoll-wait.c
@@ -239,6 +239,9 @@ static void *workerfn(void *arg)
static void nest_epollfd(struct worker *w)
{
+ if (!w)
+ return;
+
unsigned int i;
struct epoll_event ev;
int efd = multiq ? w->epollfd : epollfd;
--
2.17.1
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] [perf] Fix null pointer deference in nest_epollfd
2020-06-18 0:38 [PATCH] [perf] Fix null pointer deference in nest_epollfd Gaurav Singh
@ 2020-06-18 14:48 ` Namhyung Kim
[not found] ` <CAFAFadA3rRQxw9nyGnhn7kshRfQ_2AN+d-eCwHF-HJ_bYfYVog@mail.gmail.com>
0 siblings, 1 reply; 3+ messages in thread
From: Namhyung Kim @ 2020-06-18 14:48 UTC (permalink / raw)
To: Gaurav Singh
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Tommi Rantala,
Thomas Gleixner, open list:PERFORMANCE EVENTS SUBSYSTEM
Hello,
On Thu, Jun 18, 2020 at 9:39 AM Gaurav Singh <gaurav1086@gmail.com> wrote:
>
> Add a NULL check for worker before dereferencing.
Did you actually see a segfault due to this?
It seems it's called with NULL only if multiq is false
so there should not be a NULL dereference.
>
> Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
> ---
> tools/perf/bench/epoll-wait.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/tools/perf/bench/epoll-wait.c b/tools/perf/bench/epoll-wait.c
> index 75dca9773186..42983eb7f82e 100644
> --- a/tools/perf/bench/epoll-wait.c
> +++ b/tools/perf/bench/epoll-wait.c
> @@ -239,6 +239,9 @@ static void *workerfn(void *arg)
>
> static void nest_epollfd(struct worker *w)
> {
> + if (!w)
> + return;
> +
> unsigned int i;
> struct epoll_event ev;
> int efd = multiq ? w->epollfd : epollfd;
Maybe it's more intuitive to check w instead of multiq here.
Thanks
Namhyung
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-06-19 13:13 UTC | newest]
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2020-06-18 0:38 [PATCH] [perf] Fix null pointer deference in nest_epollfd Gaurav Singh
2020-06-18 14:48 ` Namhyung Kim
[not found] ` <CAFAFadA3rRQxw9nyGnhn7kshRfQ_2AN+d-eCwHF-HJ_bYfYVog@mail.gmail.com>
2020-06-19 13:12 ` Namhyung Kim
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