AddressSanitizer triage: fix the first invalid access before trusting later behavior

What it is

AddressSanitizer combines compiler instrumentation and a runtime to detect several memory-access errors. Clang documents compiling and linking with -fsanitize=address, using debug information for useful reports, and making a symbolizer available. Its default behavior stops at the first detected error because subsequent execution after corruption is unreliable. Clang AddressSanitizer

Why it matters

An agent may focus on the crash line and add a null check there, even though the object was freed earlier. Read the report as a lifecycle account: the access, allocation and deallocation may occur in different functions. The proposed investigation below follows the violated ownership or bounds rule.

How to apply

• Build the smallest relevant executable with the documented sanitizer configuration and matching debug symbols. Record compiler version and which libraries are instrumented.
• Retain the first complete report, including relevant allocation and release stacks. Reduce the triggering input without removing the same error category or changing the suspected lifetime relationship.
• Write the intended invariant in plain language: for example, the callback must not outlive the buffer owner, or the index must stay below the current length.
• Change the ownership, lifetime or bounds logic that violates that invariant. Avoid merely skipping the reported operation unless skipping is the intended application behavior.
• Propose a regression fixture that reaches the same boundary, then rerun it with instrumentation and in the normal supported build. Check surrounding error paths as well as the original input.

Pitfalls

A clean sanitizer run covers the paths actually executed and does not establish absence of all memory defects. Instrumentation also changes the environment, so report the configuration. Suppressions require a narrowly documented reason; they are not a fix for an unexplained report. Do not publish production inputs or secret-bearing stack context when preparing a reproducer.