52 lines
2.0 KiB
Diff
52 lines
2.0 KiB
Diff
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From f27182695d88350b48c8b9a6dce54bb513d7aa4e Mon Sep 17 00:00:00 2001
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From: Peter Jones <pjones@redhat.com>
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Date: Thu, 27 Jul 2023 15:13:08 -0400
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Subject: [PATCH] Add primitives for overflow-checked arithmetic operations.
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We need to do arithmetic on untrusted values sometimes, so this patch
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adds the following primitives as macros that wrap the compiler builtins.
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bool checked_add(TYPE addend0, TYPE addend1, TYPE *sum)
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bool checked_sub(TYPE minuend, TYPE subtrahend, TYPE *difference)
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bool checked_mul(TYPE factor0, TYPE factor1, TYPE *product)
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And also the following primitive which returns True if divisor is 0 and
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False otherwise:
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bool checked_div(TYPE dividend, TYPE divisor, TYPE *quotient)
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Signed-off-by: Peter Jones <pjones@redhat.com>
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---
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include/compiler.h | 16 ++++++++++++++++
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1 file changed, 16 insertions(+)
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diff --git a/include/compiler.h b/include/compiler.h
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index b0d595f..545a72e 100644
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--- a/include/compiler.h
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+++ b/include/compiler.h
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@@ -198,5 +198,21 @@
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#error shim has no cache_invalidate() implementation for this compiler
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#endif /* __GNUC__ */
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+#define checked_add(addend0, addend1, sum) \
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+ __builtin_add_overflow(addend0, addend1, sum)
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+#define checked_sub(minuend, subtrahend, difference) \
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+ __builtin_sub_overflow(minuend, subtrahend, difference)
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+#define checked_mul(factor0, factor1, product) \
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+ __builtin_mul_overflow(factor0, factor1, product)
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+#define checked_div(dividend, divisor, quotient) \
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+ ({ \
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+ bool _ret = True; \
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+ if ((divisor) != 0) { \
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+ _ret = False; \
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+ (quotient) = (dividend) / (divisor); \
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+ } \
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+ _ret; \
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+ })
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+
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#endif /* !COMPILER_H_ */
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// vim:fenc=utf-8:tw=75:et
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--
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2.33.0
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