linux-kernel - Re: [PATCH v4] coccinelle: misc: add array_size_dup script to detect missed overflow checks

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Date:   Wed, 24 Jun 2020 21:42:34 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Denis Efremov <efremov@...ux.com>
cc:     cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] coccinelle: misc: add array_size_dup script to detect
 missed overflow checks



On Tue, 23 Jun 2020, Denis Efremov wrote:

> Detect an opencoded expression that is used before or after
> array_size()/array3_size()/struct_size() to compute the same size.
>
> Signed-off-by: Denis Efremov <efremov@...ux.com>

Applied, thanks.

julia

> ---
> Changes in v2:
>  - python rules moved next to SmPL patterns
>  - assignment operator used
>  - struct_size patterns fixed to check only E3, since
>    E1, E2 are sizeofs of a structure and a member
>    of a structure
> Changes in v3:
>  - s/overlow/overflow/ typo fixed (thanks, Markus)
>  - \(&E1\|&E2\) changed to &\(E1\|E2\)
>  - print strings breaks removed
> Changes in v4:
>  - duplicates warning removed
>  - python2 compatability in report&&org modes added
>  - s/down the code/later/ warning changed
>  - \(E1\|E2\|subE1\|subE2\) patterns simplified to \(subE1\|subE2\)
>
>  scripts/coccinelle/misc/array_size_dup.cocci | 209 +++++++++++++++++++
>  1 file changed, 209 insertions(+)
>  create mode 100644 scripts/coccinelle/misc/array_size_dup.cocci
>
> diff --git a/scripts/coccinelle/misc/array_size_dup.cocci b/scripts/coccinelle/misc/array_size_dup.cocci
> new file mode 100644
> index 000000000000..d3d635b2d4fc
> --- /dev/null
> +++ b/scripts/coccinelle/misc/array_size_dup.cocci
> @@ -0,0 +1,209 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +///
> +/// Check for array_size(), array3_size(), struct_size() duplicates.
> +/// Three types of patterns for these functions:
> +///  1. An opencoded expression is used before array_size() to compute the same size
> +///  2. An opencoded expression is used after array_size() to compute the same size
> +/// From security point of view only first case is relevant. These functions
> +/// perform arithmetic overflow check. Thus, if we use an opencoded expression
> +/// before a call to the *_size() function we can miss an overflow.
> +///
> +// Confidence: High
> +// Copyright: (C) 2020 Denis Efremov ISPRAS
> +// Options: --no-includes --include-headers --no-loops
> +
> +virtual context
> +virtual report
> +virtual org
> +
> +@as@
> +expression E1, E2;
> +@@
> +
> +array_size(E1, E2)
> +
> +@...next@
> +expression subE1 <= as.E1;
> +expression subE2 <= as.E2;
> +expression as.E1, as.E2, E3;
> +assignment operator aop;
> +position p1, p2;
> +@@
> +
> +* E1 * E2@p1
> +  ... when != \(subE1\|subE2\) aop E3
> +      when != &\(subE1\|subE2\)
> +* array_size(E1, E2)@p2
> +
> +@...ipt:python depends on report@
> +p1 << as_next.p1;
> +p2 << as_next.p2;
> +@@
> +
> +msg = "WARNING: array_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.report.print_report(p1[0], msg)
> +
> +@...ipt:python depends on org@
> +p1 << as_next.p1;
> +p2 << as_next.p2;
> +@@
> +
> +msg = "WARNING: array_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.org.print_todo(p1[0], msg)
> +
> +@...prev@
> +expression subE1 <= as.E1;
> +expression subE2 <= as.E2;
> +expression as.E1, as.E2, E3;
> +assignment operator aop;
> +position p1, p2;
> +@@
> +
> +* array_size(E1, E2)@p1
> +  ... when != \(subE1\|subE2\) aop E3
> +      when != &\(subE1\|subE2\)
> +* E1 * E2@p2
> +
> +@...ipt:python depends on report@
> +p1 << as_prev.p1;
> +p2 << as_prev.p2;
> +@@
> +
> +msg = "WARNING: array_size is already used (line %s) to compute the same size" % (p1[0].line)
> +coccilib.report.print_report(p2[0], msg)
> +
> +@...ipt:python depends on org@
> +p1 << as_prev.p1;
> +p2 << as_prev.p2;
> +@@
> +
> +msg = "WARNING: array_size is already used (line %s) to compute the same size" % (p1[0].line)
> +coccilib.org.print_todo(p2[0], msg)
> +
> +@as3@
> +expression E1, E2, E3;
> +@@
> +
> +array3_size(E1, E2, E3)
> +
> +@..._next@
> +expression subE1 <= as3.E1;
> +expression subE2 <= as3.E2;
> +expression subE3 <= as3.E3;
> +expression as3.E1, as3.E2, as3.E3, E4;
> +assignment operator aop;
> +position p1, p2;
> +@@
> +
> +* E1 * E2 * E3@p1
> +  ... when != \(subE1\|subE2\|subE3\) aop E4
> +      when != &\(subE1\|subE2\|subE3\)
> +* array3_size(E1, E2, E3)@p2
> +
> +@...ipt:python depends on report@
> +p1 << as3_next.p1;
> +p2 << as3_next.p2;
> +@@
> +
> +msg = "WARNING: array3_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.report.print_report(p1[0], msg)
> +
> +@...ipt:python depends on org@
> +p1 << as3_next.p1;
> +p2 << as3_next.p2;
> +@@
> +
> +msg = "WARNING: array3_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.org.print_todo(p1[0], msg)
> +
> +@..._prev@
> +expression subE1 <= as3.E1;
> +expression subE2 <= as3.E2;
> +expression subE3 <= as3.E3;
> +expression as3.E1, as3.E2, as3.E3, E4;
> +assignment operator aop;
> +position p1, p2;
> +@@
> +
> +* array3_size(E1, E2, E3)@p1
> +  ... when != \(subE1\|subE2\|subE3\) aop E4
> +      when != &\(subE1\|subE2\|subE3\)
> +* E1 * E2 * E3@p2
> +
> +@...ipt:python depends on report@
> +p1 << as3_prev.p1;
> +p2 << as3_prev.p2;
> +@@
> +
> +msg = "WARNING: array3_size is already used (line %s) to compute the same size" % (p1[0].line)
> +coccilib.report.print_report(p2[0], msg)
> +
> +@...ipt:python depends on org@
> +p1 << as3_prev.p1;
> +p2 << as3_prev.p2;
> +@@
> +
> +msg = "WARNING: array3_size is already used (line %s) to compute the same size" % (p1[0].line)
> +coccilib.org.print_todo(p2[0], msg)
> +
> +@ss@
> +expression E1, E2, E3;
> +@@
> +
> +struct_size(E1, E2, E3)
> +
> +@...next@
> +expression subE3 <= ss.E3;
> +expression ss.E1, ss.E2, ss.E3, E4;
> +assignment operator aop;
> +position p1, p2;
> +@@
> +
> +* E1 * E2 + E3@p1
> +  ... when != subE3 aop E4
> +      when != &subE3
> +* struct_size(E1, E2, E3)@p2
> +
> +@...ipt:python depends on report@
> +p1 << ss_next.p1;
> +p2 << ss_next.p2;
> +@@
> +
> +msg = "WARNING: struct_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.report.print_report(p1[0], msg)
> +
> +@...ipt:python depends on org@
> +p1 << ss_next.p1;
> +p2 << ss_next.p2;
> +@@
> +
> +msg = "WARNING: struct_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.org.print_todo(p1[0], msg)
> +
> +@...prev@
> +expression subE3 <= ss.E3;
> +expression ss.E1, ss.E2, ss.E3, E4;
> +assignment operator aop;
> +position p1, p2;
> +@@
> +
> +* struct_size(E1, E2, E3)@p1
> +  ... when != subE3 aop E4
> +      when != &subE3
> +* E1 * E2 + E3@p2
> +
> +@...ipt:python depends on report@
> +p1 << ss_prev.p1;
> +p2 << ss_prev.p2;
> +@@
> +
> +msg = "WARNING: struct_size is already used (line %s) to compute the same size" % (p1[0].line)
> +coccilib.report.print_report(p2[0], msg)
> +
> +@...ipt:python depends on org@
> +p1 << ss_prev.p1;
> +p2 << ss_prev.p2;
> +@@
> +
> +msg = "WARNING: struct_size is already used (line %s) to compute the same size" % (p1[0].line)
> +coccilib.org.print_todo(p2[0], msg)
> --
> 2.26.2
>
>