• Michael Lippautz's avatar
    Reland "cppgc: Properly clear (Weak)Peristent and WeakMember pointers" · 8bdce527
    Michael Lippautz authored
    This is a reland of e0c1a349
    
    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/+/2250240Reviewed-by: 's avatarOmer Katz <omerkatz@chromium.org>
    Reviewed-by: 's avatarAnton Bikineev <bikineev@chromium.org>
    Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#68426}
    8bdce527
visitor.h 6.72 KB