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Graph/broken-memory-and-concurrency-invariants

AntiPattern

Compiler and Memory Order Bugs

broken-memory-and-concurrency-invariants

Memory-safety and concurrency invariants get broken because the code relies on compiler/runtime assumptions (paths not executed, CAS ordering too strong/weak), while externally supplied indices/pointers corrupt heap structures, leading to heap buffer overflows and illegal memory access.

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Updated7/18/2026

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30 linked nodes

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Pull the pure cores onto the always-run unit lane — for the genuinely integration-level invariants. Tension: a skipped test is not a passing test.

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alter sequence s1 cache 10;. Tension: it'll get pre-allocated 10 values at once. Outcome: The price is that it increases the amount of gaps in the sequence.

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Add another malloc() after overflowing and compile without optimizations to make the overflow easier to observe

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Technically, it's not 100% free of undefined behavior. — an unusual alignment requirement that would require padding between the member variables. Tension: Nevertheless, it should be a reliable example.

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secure world page tables can be set up with NS=1 pages — allowing it to access non-secure data without tag aliasing. Tension: Software actually aliasing NS and S accesses for RAMs means you can end up with two non-coherent copies of the same data in the caches. Outcome: allowing it to access non-secure data without tag aliasing.

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Then compiled it with `gcc -std=c99 -fno-stack-protector -static main.c` — To demonstrate the overflow, I use Linux and gcc 15.1.1. Outcome: Now exploit the buffer overflow:.

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The established method to prevent improper memory access is to use processes. — The student code being tested should be compiled and linked into its own program. Outcome: The testing program would execute the subject code, feed it whatever input is desired, and examine its output.

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Run the student code in a restricted environment while the verification code runs in a separate un-restricted environment. Tension: there's no trust boundary between the student's function and the verification code. Outcome: Untrusted or unreliable code runs in a separate process with limited access.

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Use smaller scopes where it improves correctness (e.g., declare loop counters inside the loop, such as `for(int i = 0; ...)`), and rely on the compiler/JIT for resource efficiency; avoid broader scopes to reduce the chance of stale or invalid variable usage.

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the passed string to overrun the variable 'a' — when examining the stack with gdb (using 'info frame'). Tension: it doesn't happen. Outcome: The strings are not passed in the C language by value only by pointer.

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only recompilation could grant a success. — Core Isolation. Tension: the alignment is required to be 0x1000. Outcome: Only recompilation will fix this.

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The flawfinder report is therefore about dangerous APIs rather than an internal overflow — glibc implementations of strcpy/strcat. Tension: bounds checks cannot be added without changing the API.

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The changed code invokes undefined behaviour. — Java 25 FFM API. Tension: You can't rely on always getting this behaviour. Outcome: The caller's pointer is passed in to it, but it's never used.

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Only if all threads of your program use `seq_cst` memory order for operations and fences. — The C++ guarantee of sequential consistency for data-race free programs only applies if all atomic operations are `seq_cst`, or if you use equivalent fences. Tension: One thread using a fence can't necessarily recover sequential consistency when other threads are using `relaxed` or `release` and `acquire` operations on `std::atomic`. Outcome: use `seq_cst` memory order for operations and fences.

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Ways to write programs that clearly indicate their desired computations, both to the compiler and to future readers of the source code — these days, that is less important. Tension: it remains important to give programmers expressive power. Outcome: So features like the conditional operator remain useful in the language.

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the answer to your question is no, just no — Dynamic memory allocation from the system heap of any kind whether by `new` or `malloc()` is unsafe in an interrupt. Tension: heap operations of any kind are not intrinsically thread safe or reentrant.

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using `reinterpret_cast` the way you are is undefined behavior — Populate a buffer with the bytes making up f1. Tension: No reinterpret_cast, no undefined behavior. Outcome: Populate f2 with the content of the buffer.

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self-referential structs in Rust. Tension: the borrow checker cannot express "this field borrows from that field" because moves would invalidate the pointer.

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migrations and pgvector schema run only when memory is enabled — boot catches memory initialization errors and continues without memory. Tension: normal unit tests do not require Postgres. Outcome: Tests use fake MemorySystem objects.

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Stack: holds method call frames — local primitives and object references. Tension: Heap: holds object instances and arrays.

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Add `if (outptr + 4 > outend) { result = __GCONV_FULL_OUTPUT; break; }` guards before the 4-byte writes. Tension: the SS2/SS3 branches never got the same treatment. Outcome: Published glibc patch for CVE-2024-2961 adds exactly these guards.

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unbounded memory allocation (DoS) — processing a crafted ELF file.

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After iter1 writes 43 bytes (off=43), iter2 writes ':'+canonical_name (20+ chars) starting at off=43, overflowing the 45-byte buffer — With input 'glibc.malloc.mxfast=glibc.malloc.mxfast=512' (43 bytes), the buffer is 45 bytes. Tension: overflowing the 45-byte buffer. Outcome: Verified by examining fix commit 1056e5b4c3.

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Located wordexp.c in posix/ directory. Tension: Found vulnerable arithmetic at line 160 in w_addword. Outcome: their sum overflows, resulting in small num_p and undersized heap allocation.

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NO upper-bound check exists. — With XML_PARSE_HUGE enabled. Outcome: heap OOB write.

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Never cache raw pointers into a buffer that may be reallocated.

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after each allocation that may trigger GC. Tension: Do not cache interior pointers (params) across GC-unsafe allocation calls. Outcome: Apply same fix pattern to sampled_data_continue.

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Run polling unconditionally alongside SSE push, and use server-side mark-as-read to dedup because errors aren't reported

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Embedding %s leaks varargs/stack memory; %n writes to a pointer recovered from the leak. — upd_wrtrtl at line 6994. Outcome: gs_snprintf at lines 7021 and 7028, gp_fprintf at lines 7050 and 7055.

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Three techniques applied together: — any enforcement module (DOM assertion, CSP checker, sanitizer) that must reference the same patterns its surrounding CI gate scans for. Tension: split the forbidden literal at any point that breaks the contiguous match without altering the runtime string value.

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