| Message ID | 20210804135621.31455-2-alxndr@bu.edu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Make timeouts more robust | expand |
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
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 */
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> --- tests/qtest/fuzz/generic_fuzz.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)