| commit | f999e15653eb0a13e93a7ac089f7c8b76de204ef | [log] [tgz] |
|---|---|---|
| author | Vyacheslav Egorov <vegorov@google.com> | Tue Jan 04 08:33:15 2022 +0000 |
| committer | Commit Bot <commit-bot@chromium.org> | Tue Jan 04 08:33:15 2022 +0000 |
| tree | 52d0994a45de7e450429622af8a9bd940f7bd9a3 | |
| parent | 26f5c2ae8411faba5efdc2fe335d52af0d6a1890 [diff] |
[vm] Avoid UB in CompressedStackMap payloads Having uint32_t field in UntaggedCompressedStackMaps::Payload implies 4 byte alignment of the whole structure and the field itself. We would prefer, however, to avoid this requirement because we are packing these structures tight in AOT snapshots without any padding in between. This change rewrites the implementation to use `memcpy(...)` to remove any alignment requirements. Note that this `memcpy(...)` will be optimized down to a single memory move on all platforms we currently support as they support necessary unaligned load/store instructions. This also means that the original code worked just fine, except when running under UBSAN. Fixes https://github.com/dart-lang/sdk/issues/47971 TEST=ubsan bots Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-ubsan-linux-release-x64-try,vm-kernel-ubsan-linux-release-x64-try Change-Id: I26a30123fcbc6d2c711f039f15f749913ce4d7bd Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/226100 Reviewed-by: Alexander Aprelev <aam@google.com> Commit-Queue: Slava Egorov <vegorov@google.com>
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