[PATCH 3/4] fuzz: setting bits in operand of out/write to zero

[Qiuhao Li]

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 1908062. Refined vs. Original result:

outl 0xcf8 0x8000081c            outl 0xcf8 0x8000081c
outb 0xcfc 0xc3                  outb 0xcfc 0xc3
outl 0xcf8 0x0               <-- outl 0xcf8 0x8000082f
outl 0xcf8 0x80000804            outl 0xcf8 0x80000804
outl 0xcfc 0x10000006        <-- outl 0xcfc 0x9b2765be
write 0xc300001024 0x2 0x10  <-- write 0xc300001024 0x2 0x0055
write 0xc300001028 0x1 0x5a      write 0xc300001028 0x1 0x5a
write 0xc30000101c 0x1 0x01      write 0xc30000101c 0x1 0x01
writel 0xc30000100c 0x2a6f6c63   writel 0xc30000100c 0x2a6f6c63
write 0xc300001018 0x1 0x80  <-- write 0xc300001018 0x1 0xa4
write 0x5c 0x1 0x10          <-- write 0x5c 0x1 0x19
write 0xc300003002 0x1 0x0   <-- write 0xc300003002 0x1 0x8a

Signed-off-by: Qiuhao Li <Qiuhao.Li@outlook.com>
---
 scripts/oss-fuzz/minimize_qtest_trace.py | 42 +++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/scripts/oss-fuzz/minimize_qtest_trace.py 
b/scripts/oss-fuzz/minimize_qtest_trace.py
index 855c3bcb54..f3e88064c4 100755
--- a/scripts/oss-fuzz/minimize_qtest_trace.py
+++ b/scripts/oss-fuzz/minimize_qtest_trace.py
@@ -172,7 +172,47 @@ def minimize_trace(inpath, outpath):
                     newtrace[i] = prior
                     del newtrace[i+1]
         i += 1
-    check_if_trace_crashes(newtrace, outpath)
+
+    assert(check_if_trace_crashes(newtrace, outpath))
+
+    TIMEOUT = (end-start)*2 # input is short now
+
+    # 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 accect hex with one byte zero padding
+                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
+
+    assert(check_if_trace_crashes(newtrace, outpath))
 
 
 if __name__ == '__main__':
-- 
2.25.1