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

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

[Markus Elfring]

> Changes in v2:
…
> - assignment operator used

I prefer the distinction for the application of corresponding metavariables.


> Changes in v3:
…
>  - \(&E1\|&E2\) changed to &\(E1\|E2\)

Would it be more helpful to mention the movement of the ampersand
before SmPL disjunctions?


…
>+/// Three types of patterns for these functions:

Will another adjustment be needed according to your information “duplicates warning removed”?


…
> +virtual context
> +virtual report
> +virtual org

Can the following SmPL code variant ever become more attractive?

+virtual context, report, org


…
> +expression subE1 <= as.E1;
> +expression subE2 <= as.E2;
> +expression as.E1, as.E2, E3;

How do you think about the following SmPL code variant?

+expression subE1 <= as.E1,
+           subE2 <= as.E2,
+           as.E1, as.E2, E3;


…
> +msg = "WARNING: array_size is used later (line %s) to compute the same size" % (p2[0].line)
> +coccilib.report.print_report(p1[0], msg)

Please omit the extra Python variable “msg” for the passing of such simple message objects.

What does hinder you to take the proposed script variants better into account?

Regards,
Markus

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

[Julia Lawall]

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I don't agree with any of these comments.

julia

On Tue, 23 Jun 2020, Markus Elfring wrote:

> > Changes in v2:
> …
> > - assignment operator used
>
> I prefer the distinction for the application of corresponding metavariables.
>
>
> > Changes in v3:
> …
> >  - \(&E1\|&E2\) changed to &\(E1\|E2\)
>
> Would it be more helpful to mention the movement of the ampersand
> before SmPL disjunctions?
>
>
> …
> >+/// Three types of patterns for these functions:
>
> Will another adjustment be needed according to your information “duplicates warning removed”?
>
>
> …
> > +virtual context
> > +virtual report
> > +virtual org
>
> Can the following SmPL code variant ever become more attractive?
>
> +virtual context, report, org
>
>
> …
> > +expression subE1 <= as.E1;
> > +expression subE2 <= as.E2;
> > +expression as.E1, as.E2, E3;
>
> How do you think about the following SmPL code variant?
>
> +expression subE1 <= as.E1,
> +           subE2 <= as.E2,
> +           as.E1, as.E2, E3;
>
>
> …
> > +msg = "WARNING: array_size is used later (line %s) to compute the same size" % (p2[0].line)
> > +coccilib.report.print_report(p1[0], msg)
>
> Please omit the extra Python variable “msg” for the passing of such simple message objects.
>
> What does hinder you to take the proposed script variants better into account?
>
> Regards,
> Markus
>

Re: [v4] coccinelle: misc: add array_size_dup script to detect missed overflow checks

[Markus Elfring]

> I don't agree with any of these comments.

Would we like to clarify each of the disagreements in more detail
for a more constructive patch review?

Regards,
Markus

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

[Julia Lawall]

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@linux.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)
> +
> +@as_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
> +
> +@script: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)
> +
> +@script: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)
> +
> +@as_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
> +
> +@script: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)
> +
> +@script: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)
> +
> +@as3_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
> +
> +@script: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)
> +
> +@script: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)
> +
> +@as3_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
> +
> +@script: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)
> +
> +@script: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)
> +
> +@ss_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
> +
> +@script: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)
> +
> +@script: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)
> +
> +@ss_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
> +
> +@script: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)
> +
> +@script: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
>
>

[PATCH v4] coccinelle: misc: add array_size_dup script to detect missed overflow checks

[Denis Efremov]

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@linux.com>
---
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)
+
+@as_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
+
+@script: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)
+
+@script: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)
+
+@as_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
+
+@script: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)
+
+@script: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)
+
+@as3_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
+
+@script: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)
+
+@script: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)
+
+@as3_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
+
+@script: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)
+
+@script: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)
+
+@ss_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
+
+@script: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)
+
+@script: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)
+
+@ss_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
+
+@script: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)
+
+@script: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