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authorJacob Keller <jacob.e.keller@intel.com>2023-02-27 12:24:28 -0800
committerKees Cook <keescook@chromium.org>2024-02-29 13:38:01 -0800
commite7549481255167dcdab355c539562c7ace17e111 (patch)
treeabc01d0800b8e65bc2bccad2be0aeda1981535ca /scripts/coccinelle
parent1d02f252339e2eaf3ba35b9dc77e7a1a9aa7414c (diff)
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coccinelle: semantic patch to check for potential struct_size calls
include/linux/overflow.h includes helper macros intended for calculating sizes of allocations. These macros prevent accidental overflow by saturating at SIZE_MAX. In general when calculating such sizes use of the macros is preferred. Add a semantic patch which can detect code patterns which can be replaced by struct_size. Note that I set the confidence to medium because this patch doesn't make an attempt to ensure that the relevant array is actually a flexible array. The struct_size macro does specifically require a flexible array. In many cases the detected code could be refactored to a flexible array, but this is not always possible (such as if there are multiple over-allocations). Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://lore.kernel.org/r/20230227202428.3657443-1-jacob.e.keller@intel.com Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'scripts/coccinelle')
-rw-r--r--scripts/coccinelle/misc/struct_size.cocci74
1 files changed, 74 insertions, 0 deletions
diff --git a/scripts/coccinelle/misc/struct_size.cocci b/scripts/coccinelle/misc/struct_size.cocci
new file mode 100644
index 000000000000..9b02c37438e4
--- /dev/null
+++ b/scripts/coccinelle/misc/struct_size.cocci
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+///
+/// Check for code that could use struct_size().
+///
+// Confidence: Medium
+// Author: Jacob Keller <jacob.e.keller@intel.com>
+// Copyright: (C) 2023 Intel Corporation
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual context
+virtual org
+virtual report
+
+// the overflow Kunit tests have some code which intentionally does not use
+// the macros, so we want to ignore this code when reporting potential
+// issues.
+@overflow_tests@
+identifier f = overflow_size_helpers_test;
+@@
+
+f
+
+//----------------------------------------------------------
+// For context mode
+//----------------------------------------------------------
+
+@depends on !overflow_tests && context@
+expression E1, E2;
+identifier m;
+@@
+(
+* (sizeof(*E1) + (E2 * sizeof(*E1->m)))
+)
+
+//----------------------------------------------------------
+// For patch mode
+//----------------------------------------------------------
+
+@depends on !overflow_tests && patch@
+expression E1, E2;
+identifier m;
+@@
+(
+- (sizeof(*E1) + (E2 * sizeof(*E1->m)))
++ struct_size(E1, m, E2)
+)
+
+//----------------------------------------------------------
+// For org and report mode
+//----------------------------------------------------------
+
+@r depends on !overflow_tests && (org || report)@
+expression E1, E2;
+identifier m;
+position p;
+@@
+(
+ (sizeof(*E1)@p + (E2 * sizeof(*E1->m)))
+)
+
+@script:python depends on org@
+p << r.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING should use struct_size")
+
+@script:python depends on report@
+p << r.p;
+@@
+
+msg="WARNING: Use struct_size"
+coccilib.report.print_report(p[0], msg)
+