From: Herbert Xu <herbert@gondor.apana.org.au>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: ebiggers@kernel.org, surenb@google.com, hannes@cmpxchg.org,
tj@kernel.org, lizefan.x@bytedance.com, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, corbet@lwn.net, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
stable@vger.kernel.org, kernel-team@android.com,
syzbot+cdb5dd11c97cc532efad@syzkaller.appspotmail.com
Subject: Re: [PATCH v2 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled
Date: Tue, 18 Jan 2022 17:58:17 +1100 [thread overview]
Message-ID: <YeZlCfZZkU5jyFS+@gondor.apana.org.au> (raw)
In-Reply-To: <CAHk-=wgwb6pJjvHYmOMT-yp5RYvw0pbv810Wcxdm5S7dWc-s0g@mail.gmail.com>
Linus Torvalds <torvalds@linux-foundation.org> 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@kernel.org>
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@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2022-01-18 6:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-11 7:12 [PATCH v2 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled Suren Baghdasaryan
2022-01-11 18:48 ` Eric Biggers
2022-01-11 19:11 ` Linus Torvalds
2022-01-11 19:26 ` Suren Baghdasaryan
2022-01-11 19:34 ` Linus Torvalds
2022-01-11 19:41 ` Eric Biggers
2022-01-11 19:45 ` Suren Baghdasaryan
2022-01-11 20:14 ` Linus Torvalds
2022-01-11 23:37 ` Suren Baghdasaryan
2022-01-12 11:06 ` Peter Zijlstra
2022-01-18 6:58 ` Herbert Xu [this message]
2022-01-12 14:37 ` Johannes Weiner
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