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Re: [PATCH 3/4] fuzz: setting bits in operand of out/write to zero
From: |
Alexander Bulekov |
Subject: |
Re: [PATCH 3/4] fuzz: setting bits in operand of out/write to zero |
Date: |
Mon, 21 Dec 2020 15:35:43 -0500 |
On 201220 0256, Qiuhao Li wrote:
> 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>
Looks good. One nit below.
Reviewed-by: Alexander Bulekov <alxndr@bu.edu>
> ---
> 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
^^ "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
> +
> + assert(check_if_trace_crashes(newtrace, outpath))
>
>
> if __name__ == '__main__':
> --
> 2.25.1
>