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[PATCH v4 2/7] fuzz: double the IOs to remove for every loop
From: |
Qiuhao Li |
Subject: |
[PATCH v4 2/7] fuzz: double the IOs to remove for every loop |
Date: |
Tue, 29 Dec 2020 12:40:39 +0800 |
Instead of removing IO instructions one by one, we can try deleting multiple
instructions at once. According to the locality of reference, we double the
number of instructions to remove for the next round and recover it to one
once we fail.
This patch is usually significant for large input.
Test with quadrupled trace input at:
https://bugs.launchpad.net/qemu/+bug/1890333/comments/1
Patched 1/6 version:
real 0m45.904s
user 0m16.874s
sys 0m10.042s
Refined version:
real 0m11.412s
user 0m6.888s
sys 0m3.325s
Signed-off-by: Qiuhao Li <Qiuhao.Li@outlook.com>
---
scripts/oss-fuzz/minimize_qtest_trace.py | 33 +++++++++++++++---------
1 file changed, 21 insertions(+), 12 deletions(-)
diff --git a/scripts/oss-fuzz/minimize_qtest_trace.py
b/scripts/oss-fuzz/minimize_qtest_trace.py
index aa69c7963e..0b665ae657 100755
--- a/scripts/oss-fuzz/minimize_qtest_trace.py
+++ b/scripts/oss-fuzz/minimize_qtest_trace.py
@@ -85,19 +85,28 @@ def minimize_trace(inpath, outpath):
i = 0
newtrace = trace[:]
- # For each line
+ remove_step = 1
while i < len(newtrace):
- # 1.) Try to remove it completely and reproduce the crash. If it works,
- # we're done.
- prior = newtrace[i]
- print("Trying to remove {}".format(newtrace[i]))
- # Try to remove the line completely
- newtrace[i] = ""
+ # 1.) Try to remove lines completely and reproduce the crash.
+ # If it works, we're done.
+ if (i+remove_step) >= len(newtrace):
+ remove_step = 1
+ prior = newtrace[i:i+remove_step]
+ for j in range(i, i+remove_step):
+ newtrace[j] = ""
+ print("Removing {lines} ...".format(lines=prior))
if check_if_trace_crashes(newtrace, outpath):
- i += 1
+ i += remove_step
+ # Double the number of lines to remove for next round
+ remove_step *= 2
continue
- newtrace[i] = prior
-
+ # Failed to remove multiple IOs, fast recovery
+ if remove_step > 1:
+ for j in range(i, i+remove_step):
+ newtrace[j] = prior[j-i]
+ remove_step = 1
+ continue
+ newtrace[i] = prior[0] # remove_step = 1
# 2.) Try to replace write{bwlq} commands with a write addr, len
# command. Since this can require swapping endianness, try both LE and
# BE options. We do this, so we can "trim" the writes in (3)
@@ -118,7 +127,7 @@ def minimize_trace(inpath, outpath):
if(check_if_trace_crashes(newtrace, outpath)):
break
else:
- newtrace[i] = prior
+ newtrace[i] = prior[0]
# 3.) If it is a qtest write command: write addr len data, try to split
# it into two separate write commands. If splitting the write down the
@@ -151,7 +160,7 @@ def minimize_trace(inpath, outpath):
if check_if_trace_crashes(newtrace, outpath):
i -= 1
else:
- newtrace[i] = prior
+ newtrace[i] = prior[0]
del newtrace[i+1]
i += 1
check_if_trace_crashes(newtrace, outpath)
--
2.25.1
- [PATCH v4 0/7] fuzz: improve crash case minimization, Qiuhao Li, 2020/12/28
- [PATCH v4 1/7] fuzz: accelerate non-crash detection, Qiuhao Li, 2020/12/28
- [PATCH v4 2/7] fuzz: double the IOs to remove for every loop,
Qiuhao Li <=
- [PATCH v4 3/7] fuzz: split write operand using binary approach, Qiuhao Li, 2020/12/28
- [PATCH v4 4/7] fuzz: loop the remove minimizer and refactoring, Qiuhao Li, 2020/12/28
- [PATCH v4 5/7] fuzz: set bits in operand of write/out to zero, Qiuhao Li, 2020/12/28
- [PATCH v4 6/7] fuzz: add minimization options, Qiuhao Li, 2020/12/28
- [PATCH v4 7/7] fuzz: heuristic split write based on past IOs, Qiuhao Li, 2020/12/28