On Sat, 17 Dec 2022 06:48:13 GMT, Justin King <jck...@openjdk.org> wrote:
>> This change instruments Metaspace for ASan. Metaspace allocates memory using >> `mmap`/`munmap` which ASan is not aware of. Fortunately ASan supports >> applications [manually poisoning/unpoisoning >> memory](https://github.com/google/sanitizers/wiki/AddressSanitizerManualPoisoning). >> ASan is able to detect poisoned memory, similar to `use-after-free`, and >> will raise an error similarly called `use-after-poison`. This provides and >> extra layer of defense and confidence. >> >> The header `sanitizers/address.h` defines macros for poisoning/unpoisoning >> memory regions. These macros can be used regardless of build mode. When ASan >> is not available, they are implemented using a NOOP approach which still >> compiles the arguments but does so such that they will be stripped out by >> the compiler due to being unreachable. This helps with maintenance. >> >> This also has the added benefit of making >> [LSan](https://bugs.openjdk.org/browse/JDK-8298445) more accurate and >> deterministic, as LSan will not look for pointers to malloc memory in >> poisoned memory regions. >> >> IMO the benefit of doing this greatly outweighs the cost. > > Justin King has updated the pull request incrementally with one additional > commit since the last revision: > > Exclude more zapping when ASan is in use > > Signed-off-by: Justin King <jck...@google.com> This doesn't look "too terrible", but I can't comment on the actual poisoning strategies. Cheers. src/hotspot/share/runtime/os.cpp line 949: > 947: // parent stack frames, read outside of initialized memory, and etc. So > we tell ASan to not > 948: // instrument this function. > 949: NO_SANITIE_ADDRESS void os::print_hex_dump(outputStream* st, address > start, address end, Typo: NO_SANITIE_ADDRESS ->NO_SANITIZE_ADDRESS ? src/hotspot/share/sanitizers/address.h line 2: > 1: /* > 2: * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved. Oracle didn't write this, it should have your/your-company's copyright. src/hotspot/share/sanitizers/address.h line 44: > 42: #endif > 43: #else > 44: #define NO_SANITIE_ADDRESS Typos src/hotspot/share/sanitizers/address.h line 56: > 54: #else > 55: // NOOP implementation which preserves the arguments, ensuring they still > compile, but ensures they > 56: // are stripped due to being unreachable. Why is this necessary? ------------- PR: https://git.openjdk.org/jdk/pull/11702
