This is a reland of e0c1a349ea
The issue was passing SentinelPointer (== +1) through T*.
The fix is disabling cfi unrelated cast diagnostic for the bottlenecks
(Get()). This means that nullptr is treated the same as
kSentinelPointer.
The alternative would be a DCHECK that Get() does not return
kSentinelPointer and adjusting all Member and Persistent logic that
uses Get() to work on void*. This is quite intrusive as it involves
Swap(), heterogeneous assignments, comparisons, etc.
Original change's description:
> cppgc: Properly clear (Weak)Peristent and WeakMember pointers
>
> The CL addresses two issues with (Weak)Persistent and WeakMember:
> 1. (Weak)Persistent pointers are cleared on heap teardown. Before this
> CL the pointers would contain stale values which could lead to UAF.
> 2. WeakPersistent and WeakMember are cleared using a combination of
> internal clearing methods and mutable fields which avoids the use
> of const_cast<>.
>
> Bug: chromium:1056170
> Change-Id: Ibf2b0f0856771b4f6906608cde13a6d43ebf81f3
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2248190
> Reviewed-by: Omer Katz <omerkatz@chromium.org>
> Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68394}
Bug: chromium:1056170
Change-Id: I3d74b43464c2973df1956f51b1419d755dd9f519
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2250240
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68426}
The CL addresses two issues with (Weak)Persistent and WeakMember:
1. (Weak)Persistent pointers are cleared on heap teardown. Before this
CL the pointers would contain stale values which could lead to UAF.
2. WeakPersistent and WeakMember are cleared using a combination of
internal clearing methods and mutable fields which avoids the use
of const_cast<>.
Bug: chromium:1056170
Change-Id: Ibf2b0f0856771b4f6906608cde13a6d43ebf81f3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2248190
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68394}
Unified heap support in V8 requires having another (at least internal)
heap that implements a unfied garbage collection strategy. This will
not re-use the already existing cppgc::Heap because there should be no
way in creating such a heap externally or scheduling stand-alone
garbage collections.
In order to have a common token, this CL introduces AllocationHandle
which can be passed to MakeGarbageCollected to allocate C++ objects.
V8 (soon) and the stand-alone heap both have methods to retrieve such
a handle.
This works around a problem with creating diamond class hierarchies
when a base class would be exposed on the public API level.
Fast paths for Blink are still possible because allocation handles can
be cached the same way (e.g. global, or TLS) as a heap can be cached.
Tbr: yangguo@chromium.org
Bug: chromium:1056170
Change-Id: I8e9472a2c24ef82d1178953e8429b1fd8a2344bc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2238027
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68310}
