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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>
75 lines
1.6 KiB
Plaintext
75 lines
1.6 KiB
Plaintext
// SPDX-License-Identifier: GPL-2.0-only
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///
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/// Check for code that could use struct_size().
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///
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// Confidence: Medium
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// Author: Jacob Keller <jacob.e.keller@intel.com>
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// Copyright: (C) 2023 Intel Corporation
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// Options: --no-includes --include-headers
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virtual patch
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virtual context
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virtual org
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virtual report
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// the overflow Kunit tests have some code which intentionally does not use
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// the macros, so we want to ignore this code when reporting potential
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// issues.
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@overflow_tests@
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identifier f = overflow_size_helpers_test;
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@@
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f
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//----------------------------------------------------------
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// For context mode
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//----------------------------------------------------------
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@depends on !overflow_tests && context@
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expression E1, E2;
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identifier m;
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@@
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(
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* (sizeof(*E1) + (E2 * sizeof(*E1->m)))
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)
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//----------------------------------------------------------
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// For patch mode
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//----------------------------------------------------------
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@depends on !overflow_tests && patch@
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expression E1, E2;
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identifier m;
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@@
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(
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- (sizeof(*E1) + (E2 * sizeof(*E1->m)))
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+ struct_size(E1, m, E2)
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)
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//----------------------------------------------------------
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// For org and report mode
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//----------------------------------------------------------
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@r depends on !overflow_tests && (org || report)@
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expression E1, E2;
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identifier m;
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position p;
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@@
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(
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(sizeof(*E1)@p + (E2 * sizeof(*E1->m)))
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)
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@script:python depends on org@
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p << r.p;
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@@
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coccilib.org.print_todo(p[0], "WARNING should use struct_size")
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@script:python depends on report@
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p << r.p;
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@@
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msg="WARNING: Use struct_size"
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coccilib.report.print_report(p[0], msg)
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