ac5f313624
do_div() does a 64-by-32 division.
When the divisor is unsigned long, u64, or s64,
do_div() truncates it to 32 bits, this means it
can test non-zero and be truncated to zero for division.
This semantic patch is inspired by Mateusz Guzik's patch:
commit b0ab99e773 ("sched: Fix possible divide by zero in avg_atom() calculation")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Cc: Gilles Muller <Gilles.Muller@lip6.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Matthias Maennich <maennich@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cocci@systeme.lip6.fr
Cc: linux-kernel@vger.kernel.org
156 lines
3.5 KiB
Plaintext
156 lines
3.5 KiB
Plaintext
// SPDX-License-Identifier: GPL-2.0-only
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/// do_div() does a 64-by-32 division.
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/// When the divisor is long, unsigned long, u64, or s64,
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/// do_div() truncates it to 32 bits, this means it can test
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/// non-zero and be truncated to 0 for division on 64bit platforms.
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///
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//# This makes an effort to find those inappropriate do_div() calls.
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//
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// Confidence: Moderate
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// Copyright: (C) 2020 Wen Yang, Alibaba.
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// Comments:
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// Options: --no-includes --include-headers
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virtual context
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virtual org
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virtual report
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@initialize:python@
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@@
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def get_digit_type_and_value(str):
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is_digit = False
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value = 0
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try:
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if (str.isdigit()):
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is_digit = True
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value = int(str, 0)
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elif (str.upper().endswith('ULL')):
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is_digit = True
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value = int(str[:-3], 0)
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elif (str.upper().endswith('LL')):
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is_digit = True
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value = int(str[:-2], 0)
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elif (str.upper().endswith('UL')):
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is_digit = True
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value = int(str[:-2], 0)
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elif (str.upper().endswith('L')):
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is_digit = True
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value = int(str[:-1], 0)
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elif (str.upper().endswith('U')):
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is_digit = True
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value = int(str[:-1], 0)
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except Exception as e:
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print('Error:',e)
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is_digit = False
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value = 0
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finally:
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return is_digit, value
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def filter_out_safe_constants(str):
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is_digit, value = get_digit_type_and_value(str)
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if (is_digit):
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if (value >= 0x100000000):
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return True
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else:
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return False
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else:
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return True
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def construct_warnings(suggested_fun):
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msg="WARNING: do_div() does a 64-by-32 division, please consider using %s instead."
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return msg % suggested_fun
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@depends on context@
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expression f;
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long l: script:python() { filter_out_safe_constants(l) };
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unsigned long ul : script:python() { filter_out_safe_constants(ul) };
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u64 ul64 : script:python() { filter_out_safe_constants(ul64) };
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s64 sl64 : script:python() { filter_out_safe_constants(sl64) };
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@@
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(
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* do_div(f, l);
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* do_div(f, ul);
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* do_div(f, ul64);
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* do_div(f, sl64);
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)
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@r depends on (org || report)@
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expression f;
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position p;
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long l: script:python() { filter_out_safe_constants(l) };
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unsigned long ul : script:python() { filter_out_safe_constants(ul) };
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u64 ul64 : script:python() { filter_out_safe_constants(ul64) };
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s64 sl64 : script:python() { filter_out_safe_constants(sl64) };
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@@
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(
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do_div@p(f, l);
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do_div@p(f, ul);
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do_div@p(f, ul64);
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do_div@p(f, sl64);
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)
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@script:python depends on org@
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p << r.p;
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ul << r.ul;
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@@
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coccilib.org.print_todo(p[0], construct_warnings("div64_ul"))
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@script:python depends on org@
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p << r.p;
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l << r.l;
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@@
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coccilib.org.print_todo(p[0], construct_warnings("div64_long"))
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@script:python depends on org@
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p << r.p;
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ul64 << r.ul64;
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@@
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coccilib.org.print_todo(p[0], construct_warnings("div64_u64"))
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@script:python depends on org@
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p << r.p;
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sl64 << r.sl64;
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@@
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coccilib.org.print_todo(p[0], construct_warnings("div64_s64"))
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@script:python depends on report@
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p << r.p;
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ul << r.ul;
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@@
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coccilib.report.print_report(p[0], construct_warnings("div64_ul"))
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@script:python depends on report@
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p << r.p;
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l << r.l;
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@@
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coccilib.report.print_report(p[0], construct_warnings("div64_long"))
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@script:python depends on report@
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p << r.p;
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sl64 << r.sl64;
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@@
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coccilib.report.print_report(p[0], construct_warnings("div64_s64"))
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@script:python depends on report@
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p << r.p;
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ul64 << r.ul64;
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@@
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coccilib.report.print_report(p[0], construct_warnings("div64_u64"))
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