From: Darren Kenny <darren.kenny@oracle.com>
To: Alexander Bulekov <alxndr@bu.edu>, qemu-devel@nongnu.org
Cc: "Laurent Vivier" <lvivier@redhat.com>,
"Thomas Huth" <thuth@redhat.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Alexander Bulekov" <alxndr@bu.edu>,
"Bandan Das" <bsd@redhat.com>,
stefanha@redhat.com, "Paolo Bonzini" <pbonzini@redhat.com>
Subject: Re: [PATCH 1/2] fuzz: use ITIMER_REAL for timeouts
Date: Wed, 04 Aug 2021 16:34:22 +0100 [thread overview]
Message-ID: <m27dh1i5q9.fsf@oracle.com> (raw)
In-Reply-To: <20210804135621.31455-2-alxndr@bu.edu>
On Wednesday, 2021-08-04 at 09:56:20 -04, Alexander Bulekov wrote:
> Using ITIMER_VIRTUAL is a bad idea, if the fuzzer hits a blocking
> syscall - e.g. ppoll with a NULL timespec. This causes timeout issues
> while fuzzing some block-device code. Fix that by using wall-clock time.
> This might cause inputs to timeout sometimes due to scheduling
> effects/ambient load, but it is better than bringing the entire fuzzing
> process to a halt.
>
> Based-on: <20210713150037.9297-1-alxndr@bu.edu>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
> ---
> tests/qtest/fuzz/generic_fuzz.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tests/qtest/fuzz/generic_fuzz.c b/tests/qtest/fuzz/generic_fuzz.c
> index 3e8ce29227..de427a3727 100644
> --- a/tests/qtest/fuzz/generic_fuzz.c
> +++ b/tests/qtest/fuzz/generic_fuzz.c
> @@ -695,7 +695,7 @@ static void generic_fuzz(QTestState *s, const unsigned char *Data, size_t Size)
> while (cmd && Size) {
> /* Reset the timeout, each time we run a new command */
> if (timeout) {
> - setitimer(ITIMER_VIRTUAL, &timer, NULL);
> + setitimer(ITIMER_REAL, &timer, NULL);
> }
>
> /* Get the length until the next command or end of input */
> --
> 2.30.2
next prev parent reply other threads:[~2021-08-04 17:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 13:56 [PATCH 0/2] Make timeouts more robust Alexander Bulekov
2021-08-04 13:56 ` [PATCH 1/2] fuzz: use ITIMER_REAL for timeouts Alexander Bulekov
2021-08-04 15:34 ` Darren Kenny [this message]
2021-08-04 13:56 ` [PATCH 2/2] fuzz: unblock SIGALRM so the timeout works Alexander Bulekov
2021-08-04 15:33 ` Darren Kenny
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