Re: [PATCH v2 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled

[Herbert Xu]

Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Of course, in practice, for pointers, the whole "dereference off a
> pointer" on the read side *does* imply a barrier in all relevant
> situations. So yes, a smp_store_release() -> READ_ONCE() does work in
> practice, although it's technically wrong (in particular, it's wrong
> on alpha, because of the completely broken memory ordering that alpha
> has that doesn't even honor data dependencies as read-side orderings)

READ_ONCE has contained the alpha barrier since 2017:

commit 76ebbe78f7390aee075a7f3768af197ded1bdfbb
Author: Will Deacon <will@xxxxxxxxxx>
Date:   Tue Oct 24 11:22:47 2017 +0100

    locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
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