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fuzz: set bits in operand of write/out to zero 

Simplifying the crash cases by opportunistically setting bits in operands of
out/write to zero may help to debug, since usually bit one means turn on or
trigger a function while zero is the default turn-off setting.

Tested bug https://bugs.launchpad.net/qemu/+bug/1908062

Signed-off-by: Qiuhao Li <Qiuhao.Li@outlook.com>
Reviewed-by: Alexander Bulekov <alxndr@bu.edu>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <SYCPR01MB3502C84B6346A3E3DE708C7BFCAB0@SYCPR01MB3502.ausprd01.prod.outlook.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
master
Qiuhao Li 2021-01-11 14:11:50 +08:00 committed by Thomas Huth
parent 247ab240c2
commit 9d20f2af53
1 changed files with 39 additions and 0 deletions
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39
scripts/oss-fuzz/minimize_qtest_trace.py
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@ -167,6 +167,42 @@ def remove_lines(newtrace, outpath):
i += 1
def clear_bits(newtrace, outpath):
# try setting bits in operands of out/write to zero
i = 0
while i < len(newtrace):
if (not newtrace[i].startswith("write ") and not
newtrace[i].startswith("out")):
i += 1
continue
# write ADDR SIZE DATA
# outx ADDR VALUE
print("\nzero setting bits: {}".format(newtrace[i]))
prefix = " ".join(newtrace[i].split()[:-1])
data = newtrace[i].split()[-1]
data_bin = bin(int(data, 16))
data_bin_list = list(data_bin)
for j in range(2, len(data_bin_list)):
prior = newtrace[i]
if (data_bin_list[j] == '1'):
data_bin_list[j] = '0'
data_try = hex(int("".join(data_bin_list), 2))
# It seems qtest only accepts padded hex-values.
if len(data_try) % 2 == 1:
data_try = data_try[:2] + "0" + data_try[2:-1]
newtrace[i] = "{prefix} {data_try}\n".format(
prefix=prefix,
data_try=data_try)
if not check_if_trace_crashes(newtrace, outpath):
data_bin_list[j] = '1'
newtrace[i] = prior
i += 1
def minimize_trace(inpath, outpath):
global TIMEOUT
with open(inpath) as f:
@ -187,7 +223,10 @@ def minimize_trace(inpath, outpath):
old_len = len(newtrace)
remove_lines(newtrace, outpath)
newtrace = list(filter(lambda s: s != "", newtrace))
assert(check_if_trace_crashes(newtrace, outpath))
# set bits to zero
clear_bits(newtrace, outpath)
assert(check_if_trace_crashes(newtrace, outpath))