From: Linus Torvalds <torvalds@linux-foundation.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Naveen N Rao <naveen@kernel.org>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Darren Hart <dvhart@infradead.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Andre Almeida <andrealmeid@igalia.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Laight <david.laight.linux@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/5] uaccess: Add speculation barrier to copy_from_user_iter()
Date: Sun, 22 Jun 2025 09:57:20 -0700 [thread overview]
Message-ID: <CAHk-=wj4P6p1kBVW7aJbWAOGJZkB7fXFmwaXLieBRhjmvnWgvQ@mail.gmail.com> (raw)
In-Reply-To: <f4b2a32853b5daba7aeac9e9b96ec1ab88981589.1750585239.git.christophe.leroy@csgroup.eu>
On Sun, 22 Jun 2025 at 02:52, Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
> The results of "access_ok()" can be mis-speculated.
Hmm. This code is critical. I think it should be converted to use that
masked address thing if we have to add it here.
And at some point this access_ok() didn't even exist, because we check
the addresses at iter creation time. So this one might be a "belt and
suspenders" check, rather than something critical.
(Although I also suspect that when we added ITER_UBUF we might have
created cases where those user addresses aren't checked at iter
creation time any more).
Linus
next prev parent reply other threads:[~2025-06-22 17:04 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-22 9:52 [PATCH 0/5] powerpc: Implement masked user access Christophe Leroy
2025-06-22 9:52 ` [PATCH 1/5] uaccess: Add masked_user_{read/write}_access_begin Christophe Leroy
2025-06-22 16:35 ` David Laight
2025-06-24 5:34 ` Christophe Leroy
2025-06-22 9:52 ` [PATCH 2/5] uaccess: Add speculation barrier to copy_from_user_iter() Christophe Leroy
2025-06-22 16:52 ` David Laight
2025-06-22 16:57 ` Linus Torvalds [this message]
2025-06-22 20:18 ` David Laight
2025-06-24 5:49 ` Christophe Leroy
2025-06-24 8:07 ` David Laight
2025-06-24 15:15 ` Linus Torvalds
2025-06-22 9:52 ` [PATCH 3/5] powerpc: Remove unused size parametre to KUAP enabling/disabling functions Christophe Leroy
2025-06-22 9:52 ` [PATCH 4/5] powerpc: Move barrier_nospec() out of allow_read_{from/write}_user() Christophe Leroy
2025-06-22 9:52 ` [PATCH 5/5] powerpc: Implement masked user access Christophe Leroy
2025-06-22 17:13 ` David Laight
2025-06-22 17:40 ` Linus Torvalds
2025-06-22 19:51 ` David Laight
2025-06-22 18:57 ` Segher Boessenkool
2025-06-22 16:20 ` [PATCH 0/5] " David Laight
2025-06-24 5:27 ` Christophe Leroy
2025-06-24 8:32 ` David Laight
2025-06-24 21:37 ` Segher Boessenkool
2025-06-25 8:30 ` David Laight
2025-06-24 13:17 ` Segher Boessenkool
2025-06-24 16:50 ` David Laight
2025-06-24 18:25 ` Segher Boessenkool
2025-06-24 21:08 ` David Laight
2025-06-26 5:56 ` Christophe Leroy
2025-06-26 22:01 ` Segher Boessenkool
2025-07-05 10:55 ` Christophe Leroy
2025-07-05 11:42 ` Segher Boessenkool
2025-07-05 18:33 ` David Laight
2025-07-05 20:15 ` Segher Boessenkool
2025-07-05 21:05 ` David Laight
2025-07-05 21:37 ` Segher Boessenkool
2025-06-26 21:39 ` Segher Boessenkool
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