Add UBSan flags to Clang builds for enhanced runtime safety - #16
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Add UBSan flags to Clang builds for enhanced runtime safety#16assisted-by-ai wants to merge 3 commits into
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Integrated wiki changes. Will add flags where appropriate (including to kloak). |
ArrayBolt3
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Apr 15, 2026
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| #ifeq (,$(findstring clang,$(CC_VERSION))) # if clang | ||
| #WARN_CFLAGS += # | ||
| #endif | ||
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| # IMPORTANT: Do NOT remove -ftrapv from the list of flags, it is used to allow | ||
| # signed integer arithmetic without explicit overflow checks. | ||
| FORTIFY_CFLAGS := -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 \ | ||
| -fstack-clash-protection -fstack-protector-all \ | ||
| -fno-delete-null-pointer-checks -fno-strict-overflow -fno-strict-aliasing \ | ||
| -fstrict-flex-arrays=3 -ftrapv -ftrivial-auto-var-init=pattern | ||
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| ifneq (,$(findstring clang,$(CC_VERSION))) # if clang | ||
| FORTIFY_CFLAGS += -fsanitize=undefined -fsanitize-minimal-runtime -fno-sanitize-recover=all | ||
| endif | ||
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This might be a good idea, but is rejected for now. As per the compiler_hardening wiki page:
Note: It is unclear whether this actually provides any meaningful level of hardening. Omitting these flags may be desirable even with Clang.
adrelanos
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May 11, 2026
Replace secrets: inherit with explicit single-secret map.
Replaces the empty commented-out Clang placeholder with working -fsanitize=undefined -fsanitize-minimal-runtime -fno-sanitize-recover=all flags, guarded by ifneq so they only apply when building with Clang. Also fixes the original placeholder's ifeq/ifneq logic inversion. https://claude.ai/code/session_01E8Jai7NViAgjrdJ6Us48Qd
Add -Wformat-truncation and -fno-strict-overflow to shared section. Add -fzero-call-used-regs=all to both summary command blocks. Add -Wformat-truncation and -fno-strict-overflow to both summary command blocks. https://claude.ai/code/session_01E8Jai7NViAgjrdJ6Us48Qd
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Summary
This change enhances the security hardening flags used when compiling with Clang by adding undefined behavior sanitizer (UBSan) instrumentation to catch runtime errors at compile time.
Key Changes
-fsanitize=undefined: Enables undefined behavior sanitization-fsanitize-minimal-runtime: Uses minimal UBSan runtime overhead-fno-sanitize-recover=all: Causes the program to halt on first UBSan error instead of continuingFORTIFY_CFLAGSwhen Clang is detectedImplementation Details
The new Clang-specific flags are conditionally added using
ifneqto detect Clang in the compiler version string, ensuring these UBSan options (which may not be supported by GCC in the same way) only apply to Clang builds. This provides additional runtime safety checks for undefined behavior while maintaining compatibility with other compilers.https://claude.ai/code/session_01E8Jai7NViAgjrdJ6Us48Qd