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Graph/precheck-read-unsafe-interrupt-mutex

AntiPattern

Unsafe Bounds & Concurrency

precheck-read-unsafe-interrupt-mutex

Read operations can occur before bounds or NULL checks, and shared-state cleanup relies on mutexes that can’t be safely taken during interrupts, leaving memory access and lock lifecycle out of order.

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Updated5/30/2026

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30 linked nodes

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you can use Zustand getters and optimistic update — multiple or rapid clicks could actually cause the updates to be executed but out of order. Tension: no optimistic update so u see that delay (lag) you said about.

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As long as you lock more than a single thing at a time, you risk deadlocks. — lock more than a single thing at a time. Tension: You hold B waiting for A, they hold A waiting for B. Outcome: one of you has to abort or you're stuck.

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provided it's called within the same process — workers might be pre-forked. Tension: the cache doesn't work across processes. Outcome: each process got its own cache.

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any time you have an I/O bound process with lots of idle time — waiting for user input, waiting for a TLS handshake. Tension: wrapping it in an async task can let other code run.

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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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In general this calls for a mutex. — If the language does not provide mutexes out of the box. Outcome: you can create a mutex.

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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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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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depending on your latency budget. Outcome: Same idea, but the state lives outside the process boundary.

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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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Or you can increment value in one query — for READ_COMMITTED. Tension: There are solutions for READ_COMMITTED:.

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Use virtual threads for blocking DB/IO work to improve scalability under the same small pool, or switch to a reactive database driver/event-loop model to avoid blocking carrier threads; adjust concurrency/throttling accordingly (semaphore/backpressure) rather than assuming the current JDBC + thread pool design remains optimal.

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Your code doesn't use any shared state (or even objects) between the different threads — running this code in a multithreaded environment. Tension: The only thing that may looks marignally relevant is calling the static `OPCPackage.open` method. Outcome: there shouldn't be any problem running this code in a multithreaded environment.

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Use synchronization primitives, locks, or other publication mechanisms that establish a happens-before between the write and subsequent read

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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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There are workarounds, depending on your usecase — calling `.notify_one()` / `.notify_all()` on a destructed `std::atomic`. Tension: There is a C++ Paper - P2616R4 - which would fix this problem. Outcome: using `std::binary_semaphore` delegating `.wait()` and `.notify_xxx()` to a separate atomic variable that has a longer lifetime manually call the futex syscalls and bypass the stdlib.

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node* p = head_.load(std::memory_order_acquire); // acquire is necessary — while (p && !head_.compare_exchange_weak(p, p->next,. Outcome: `CAS_weak(p, p->next, acquire, acquire)`.

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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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the goroutine blocks forever on the channel send because nobody is reading — When the parent context is cancelled, the goroutine blocks forever on the channel send because nobody is reading. Tension: if the result is ready at the exact moment the context cancels, which case fires?

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With buffered channels, is there a risk of the goroutine sending one more item after cancellation? — With buffered channels. Tension: the goroutine might send one more item after cancellation.

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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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Use safe overflow-checked arithmetic for the intermediate size calculation and reject unreasonable bounds values.

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

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