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From: Thomas Gleixner <tglx@linutronix.de>
To: Pranav Tyagi <pranav.tyagi03@gmail.com>
Cc: "Ingo Molnar" <mingo@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Darren Hart" <dvhart@infradead.org>,
	"Davidlohr Bueso" <dave@stgolabs.net>,
	"André Almeida" <andrealmeid@igalia.com>,
	linux-kernel@vger.kernel.org, jann@thejh.net,
	keescook@chromium.org, skhan@linuxfoundation.org,
	linux-kernel-mentees@lists.linux.dev
Subject: Re: [PATCH] futex: don't leak robust_list pointer on exec race
Date: Wed, 30 Jul 2025 19:16:48 +0200	[thread overview]
Message-ID: <87pldhioov.ffs@tglx> (raw)
In-Reply-To: <CAH4c4jKmj2gwmW2LS8CuGyw6phtiN+=_Bef8_pSEzjnbsqPOeg@mail.gmail.com>

On Wed, Jul 30 2025 at 20:21, Pranav Tyagi wrote:
> On Fri, Jun 13, 2025 at 6:38 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> I face a small issue while refactoring the common code in a helper.
>
> The main obstacle to a full refactor is that the native and compat
> syscalls use different user-visible types (size_t vs compat_size_t,
> struct robust_list_head * vs compat_uptr_t). Because put_user() is
> type-checked at compile-time, I can’t unify both into one function
> without either unsafe casting or weakening type safety (this is as far
> as I understand).
>
> The best I can do is refactor the common task lookup/permission
> logic into a helper, and leave ABI-specific put_user() calls in thin wrappers.

These are two different SYSCALL() implementations, so they
can deal with the difference sizes of put_user() there.

Thanks,

        tglx

  reply	other threads:[~2025-07-30 17:16 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-07  6:44 [PATCH] futex: don't leak robust_list pointer on exec race Pranav Tyagi
2025-06-09  9:45 ` Thomas Gleixner
2025-06-11 14:03   ` Pranav Tyagi
2025-06-13 13:08     ` Thomas Gleixner
2025-06-18  6:20       ` Pranav Tyagi
2025-07-24 17:37         ` Kees Cook
2025-07-25 11:43           ` Pranav Tyagi
2025-07-30 14:51       ` Pranav Tyagi
2025-07-30 17:16         ` Thomas Gleixner [this message]
2025-08-04  7:01           ` Pranav Tyagi

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