Date:   Thu, 18 Jun 2020 13:23:08 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     Julia Lawall <Julia.Lawall@...6.fr>
Cc:     Denis Efremov <efremov@...ux.com>, cocci@...teme.lip6.fr,
        linux-kernel@...r.kernel.org,
        "Gustavo A . R . Silva" <garsilva@...eddedor.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH v2] coccinelle: misc: add array_size_dup script to detect missed overlow checks

Detect an opencoded expression that is used before or after
array_size()/array3_size()/struct_size() to compute the same size.

Cc: Gustavo A. R. Silva <garsilva@...eddedor.com>
Cc: Kees Cook <keescook@...omium.org>
Signed-off-by: Denis Efremov <efremov@...ux.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

 scripts/coccinelle/misc/array_size_dup.cocci | 309 +++++++++++++++++++
 1 file changed, 309 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..c5214310285c
--- /dev/null
+++ b/scripts/coccinelle/misc/array_size_dup.cocci
@@ -0,0 +1,309 @@
+// 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
+///  3. Consecutive calls of array_size() with the same values
+/// 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 != \(E1\|E2\|subE1\|subE2\) aop E3
+      when != \(&E1\|&E2\|&subE1\|&subE2\)
+* array_size(E1, E2)@p2
+
+@...ipt:python depends on report@
+p1 << as_next.p1;
+p2 << as_next.p2;
+@@
+
+coccilib.report.print_report(p1[0],
+f"WARNING: array_size is used down the code (line {p2[0].line}) to compute \
+the same size")
+
+@...ipt:python depends on org@
+p1 << as_next.p1;
+p2 << as_next.p2;
+@@
+
+coccilib.org.print_todo(p1[0],
+f"WARNING: array_size is used down the code (line {p2[0].line}) to compute \
+the same size")
+
+@...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 != \(E1\|E2\|subE1\|subE2\) aop E3
+      when != \(&E1\|&E2\|&subE1\|&subE2\)
+* E1 * E2@p2
+
+@...ipt:python depends on report@
+p1 << as_prev.p1;
+p2 << as_prev.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+f"WARNING: array_size is already used (line {p1[0].line}) to compute \
+the same size")
+
+@...ipt:python depends on org@
+p1 << as_prev.p1;
+p2 << as_prev.p2;
+@@
+
+coccilib.org.print_todo(p2[0],
+f"WARNING: array_size is already used (line {p1[0].line}) to compute \
+the same size")
+
+@...dup@
+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 != \(E1\|E2\|subE1\|subE2\) aop E3
+      when != \(&E1\|&E2\|&subE1\|&subE2\)
+* array_size(E1, E2)@p2
+
+@...ipt:python depends on report@
+p1 << as_dup.p1;
+p2 << as_dup.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+f"WARNING: same array_size (line {p1[0].line})")
+
+@...ipt:python depends on org@
+p1 << as_dup.p1;
+p2 << as_dup.p2;
+@@
+
+coccilib.org.print_todo(p2[0],
+f"WARNING: same array_size (line {p1[0].line})")
+
+@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 != \(E1\|E2\|E3\|subE1\|subE2\|subE3\) aop E4
+      when != \(&E1\|&E2\|&E3\|&subE1\|&subE2\|&subE3\)
+* array3_size(E1, E2, E3)@p2
+
+@...ipt:python depends on report@
+p1 << as3_next.p1;
+p2 << as3_next.p2;
+@@
+
+coccilib.report.print_report(p1[0],
+f"WARNING: array3_size is used down the code (line {p2[0].line}) to compute \
+the same size")
+
+@...ipt:python depends on org@
+p1 << as3_next.p1;
+p2 << as3_next.p2;
+@@
+
+coccilib.org.print_todo(p1[0],
+f"WARNING: array3_size is used down the code (line {p2[0].line}) to compute \
+the same size")
+
+@..._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 != \(E1\|E2\|E3\|subE1\|subE2\|subE3\) aop E4
+      when != \(&E1\|&E2\|&E3\|&subE1\|&subE2\|&subE3\)
+* E1 * E2 * E3@p2
+
+@...ipt:python depends on report@
+p1 << as3_prev.p1;
+p2 << as3_prev.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+f"WARNING: array3_size is already used (line {p1[0].line}) to compute \
+the same size")
+
+@...ipt:python depends on org@
+p1 << as3_prev.p1;
+p2 << as3_prev.p2;
+@@
+
+coccilib.org.print_todo(p2[0],
+f"WARNING: array3_size is already used (line {p1[0].line}) to compute \
+the same size")
+
+@..._dup@
+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 != \(E1\|E2\|E3\|subE1\|subE2\|subE3\) aop E4
+      when != \(&E1\|&E2\|&E3\|&subE1\|&subE2\|&subE3\)
+* array3_size(E1, E2, E3)@p2
+
+@...ipt:python depends on report@
+p1 << as3_dup.p1;
+p2 << as3_dup.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+f"WARNING: same array3_size (line {p1[0].line})")
+
+@...ipt:python depends on org@
+p1 << as3_dup.p1;
+p2 << as3_dup.p2;
+@@
+
+coccilib.org.print_todo(p2[0],
+f"WARNING: same array3_size (line {p1[0].line})")
+
+@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 != \(E3\|subE3\) aop E4
+      when != \(&E3\|&subE3\)
+* struct_size(E1, E2, E3)@p2
+
+@...ipt:python depends on report@
+p1 << ss_next.p1;
+p2 << ss_next.p2;
+@@
+
+coccilib.report.print_report(p1[0],
+f"WARNING: struct_size is used down the code (line {p2[0].line}) to compute \
+the same size")
+
+@...ipt:python depends on org@
+p1 << ss_next.p1;
+p2 << ss_next.p2;
+@@
+
+coccilib.org.print_todo(p1[0],
+f"WARNING: struct_size is used down the code (line {p2[0].line}) to compute \
+the same size")
+
+@...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 != \(E3\|subE3\) aop E4
+      when != \(&E3\|&subE3\)
+* E1 * E2 + E3@p2
+
+@...ipt:python depends on report@
+p1 << ss_prev.p1;
+p2 << ss_prev.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+f"WARNING: struct_size is already used (line {p1[0].line}) to compute \
+the same size")
+
+@...ipt:python depends on org@
+p1 << ss_prev.p1;
+p2 << ss_prev.p2;
+@@
+
+coccilib.org.print_todo(p2[0],
+f"WARNING: struct_size is already used (line {p1[0].line}) to compute \
+the same size")
+
+@...dup@
+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 != \(E3\|subE3\) aop E4
+      when != \(&E3\|&subE3\)
+* struct_size(E1, E2, E3)@p2
+
+@...ipt:python depends on report@
+p1 << ss_dup.p1;
+p2 << ss_dup.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+f"WARNING: same struct_size (line {p1[0].line})")
+
+@...ipt:python depends on org@
+p1 << ss_dup.p1;
+p2 << ss_dup.p2;
+@@
+
+coccilib.org.print_todo(p2[0],
+f"WARNING: same struct_size (line {p1[0].line})")
-- 
2.26.2

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