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From:   Denis Efremov <efremov@linux.com>
To:     Julia Lawall <Julia.Lawall@lip6.fr>
Cc:     Denis Efremov <efremov@linux.com>, cocci@systeme.lip6.fr,
        linux-kernel@vger.kernel.org,
        "Gustavo A . R . Silva" <garsilva@embeddedor.com>,
        Kees Cook <keescook@chromium.org>
Subject: [PATCH v3] coccinelle: misc: add array_size_dup script to detect missed overflow checks
Date:   Fri, 19 Jun 2020 16:13:13 +0300
Message-Id: <20200619131313.15468-1-efremov@linux.com>
In-Reply-To: <20200615102045.4558-1-efremov@linux.com>
References: <20200615102045.4558-1-efremov@linux.com>
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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@embeddedor.com>
Cc: Kees Cook <keescook@chromium.org>
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

 scripts/coccinelle/misc/array_size_dup.cocci | 297 +++++++++++++++++++
 1 file changed, 297 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..d03740257e97
--- /dev/null
+++ b/scripts/coccinelle/misc/array_size_dup.cocci
@@ -0,0 +1,297 @@
+// 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)
+
+@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 != \(E1\|E2\|subE1\|subE2\) aop E3
+      when != &\(E1\|E2\|subE1\|subE2\)
+* array_size(E1, E2)@p2
+
+@script: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")
+
+@script: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")
+
+@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 != \(E1\|E2\|subE1\|subE2\) aop E3
+      when != &\(E1\|E2\|subE1\|subE2\)
+* E1 * E2@p2
+
+@script: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")
+
+@script: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")
+
+@as_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
+
+@script: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})")
+
+@script: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)
+
+@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 != \(E1\|E2\|E3\|subE1\|subE2\|subE3\) aop E4
+      when != &\(E1\|E2\|E3\|subE1\|subE2\|subE3\)
+* array3_size(E1, E2, E3)@p2
+
+@script: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")
+
+@script: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")
+
+@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 != \(E1\|E2\|E3\|subE1\|subE2\|subE3\) aop E4
+      when != &\(E1\|E2\|E3\|subE1\|subE2\|subE3\)
+* E1 * E2 * E3@p2
+
+@script: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")
+
+@script: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")
+
+@as3_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
+
+@script: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})")
+
+@script: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)
+
+@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 != \(E3\|subE3\) aop E4
+      when != &\(E3\|subE3\)
+* struct_size(E1, E2, E3)@p2
+
+@script: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")
+
+@script: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")
+
+@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 != \(E3\|subE3\) aop E4
+      when != &\(E3\|subE3\)
+* E1 * E2 + E3@p2
+
+@script: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")
+
+@script: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")
+
+@ss_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
+
+@script: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})")
+
+@script: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