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From: Alexander Bulekov <alxndr@bu.edu>
To: qemu-devel@nongnu.org
Cc: bonzini@redhat.com, peter.maydell@linaro.org,
	Darren Kenny <darren.kenny@oracle.com>,
	Alexander Bulekov <alxndr@bu.edu>
Subject: [PULL v3 5/8] fuzz: use ITIMER_REAL for timeouts
Date: Wed,  1 Sep 2021 07:50:01 -0400	[thread overview]
Message-ID: <20210901115004.34768-6-alxndr@bu.edu> (raw)
In-Reply-To: <20210901115004.34768-1-alxndr@bu.edu>

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



  parent reply	other threads:[~2021-09-01 12:02 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 11:49 [PULL v3 0/8] Fuzzing Patches for 2021-09-01 Alexander Bulekov
2021-09-01 11:49 ` [PULL v3 1/8] fuzz: fix sparse memory access in the DMA callback Alexander Bulekov
2021-09-01 11:49 ` [PULL v3 2/8] fuzz: adjust timeout to allow for longer inputs Alexander Bulekov
2021-09-01 11:49 ` [PULL v3 3/8] fuzz: make object-name matching case-insensitive Alexander Bulekov
2021-09-01 11:50 ` [PULL v3 4/8] fuzz: add an instrumentation filter Alexander Bulekov
2021-09-01 11:50 ` Alexander Bulekov [this message]
2021-09-01 11:50 ` [PULL v3 6/8] fuzz: unblock SIGALRM so the timeout works Alexander Bulekov
2021-09-01 11:50 ` [PULL v3 7/8] MAINTAINERS: Add myself as a reviewer for Device Fuzzing Alexander Bulekov
2021-09-01 11:50 ` [PULL v3 8/8] MAINTAINERS: add fuzzing reviewer Alexander Bulekov
2021-09-03  7:26 ` [PULL v3 0/8] Fuzzing Patches for 2021-09-01 Peter Maydell

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