From: Peter Xu <peterx@redhat.com>
To: Tal Zussman <tz2294@columbia.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
David Hildenbrand <david@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Pavel Emelyanov <xemul@parallels.com>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/3] userfaultfd: correctly prevent registering VM_DROPPABLE regions
Date: Wed, 4 Jun 2025 11:17:06 -0400 [thread overview]
Message-ID: <aEBjct3IJiDX-w3P@x1.local> (raw)
In-Reply-To: <20250603-uffd-fixes-v1-1-9c638c73f047@columbia.edu>
On Tue, Jun 03, 2025 at 06:14:20PM -0400, Tal Zussman wrote:
> vma_can_userfault() masks off non-userfaultfd VM flags from vm_flags.
> The vm_flags & VM_DROPPABLE test will then always be false, incorrectly
> allowing VM_DROPPABLE regions to be registered with userfaultfd.
>
> Additionally, vm_flags is not guaranteed to correspond to the actual
> VMA's flags. Fix this test by checking the VMA's flags directly.
>
> Link: https://lore.kernel.org/linux-mm/5a875a3a-2243-4eab-856f-bc53ccfec3ea@redhat.com/
> Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings")
> Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Acked-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
next prev parent reply other threads:[~2025-06-04 15:17 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-03 22:14 [PATCH 0/3] mm: userfaultfd: assorted fixes and cleanups Tal Zussman
2025-06-03 22:14 ` [PATCH 1/3] userfaultfd: correctly prevent registering VM_DROPPABLE regions Tal Zussman
2025-06-04 13:19 ` David Hildenbrand
2025-06-04 15:17 ` Peter Xu [this message]
2025-06-03 22:14 ` [PATCH 2/3] userfaultfd: prevent unregistering VMAs through a different userfaultfd Tal Zussman
2025-06-04 0:52 ` James Houghton
2025-06-05 20:56 ` Tal Zussman
2025-06-04 13:23 ` David Hildenbrand
2025-06-04 15:09 ` Peter Xu
2025-06-05 21:06 ` David Hildenbrand
2025-06-05 21:15 ` Tal Zussman
2025-06-06 13:03 ` Peter Xu
2025-06-06 13:15 ` David Hildenbrand
2025-06-05 21:11 ` Tal Zussman
2025-06-06 13:24 ` Peter Xu
2025-06-06 19:15 ` Tal Zussman
2025-06-05 21:06 ` Tal Zussman
2025-06-03 22:14 ` [PATCH 3/3] userfaultfd: remove UFFD_CLOEXEC, UFFD_NONBLOCK, and UFFD_FLAGS_SET Tal Zussman
2025-06-04 13:24 ` David Hildenbrand
2025-06-04 15:17 ` Peter Xu
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