From: Andrew Morton <akpm@linux-foundation.org>
To: Tal Zussman <tz2294@columbia.edu>
Cc: Peter Xu <peterx@redhat.com>,
"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>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v2 1/4] userfaultfd: correctly prevent registering VM_DROPPABLE regions
Date: Sat, 7 Jun 2025 15:04:38 -0700 [thread overview]
Message-ID: <20250607150438.4439e19f74693445212d93df@linux-foundation.org> (raw)
In-Reply-To: <20250607-uffd-fixes-v2-1-339dafe9a2fe@columbia.edu>
On Sat, 07 Jun 2025 02:40:00 -0400 Tal Zussman <tz2294@columbia.edu> 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.
Wondering if we should backport this. afaict we don't know the
userspace impact of this because nobody has tried it!
next prev parent reply other threads:[~2025-06-07 22:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-07 6:39 [PATCH v2 0/4] mm: userfaultfd: assorted fixes and cleanups Tal Zussman
2025-06-07 6:40 ` [PATCH v2 1/4] userfaultfd: correctly prevent registering VM_DROPPABLE regions Tal Zussman
2025-06-07 14:40 ` Jason A. Donenfeld
2025-06-07 22:04 ` Andrew Morton [this message]
2025-06-09 15:02 ` Peter Xu
2025-06-07 6:40 ` [PATCH v2 2/4] userfaultfd: remove (VM_)BUG_ON()s Tal Zussman
2025-06-10 7:26 ` David Hildenbrand
2025-06-17 23:10 ` Tal Zussman
2025-06-23 15:18 ` David Hildenbrand
2025-06-10 13:11 ` Peter Xu
2025-06-10 13:17 ` David Hildenbrand
2025-06-07 6:40 ` [PATCH v2 3/4] userfaultfd: prevent unregistering VMAs through a different userfaultfd Tal Zussman
2025-06-10 7:30 ` David Hildenbrand
2025-06-17 20:50 ` Tal Zussman
2025-06-07 6:40 ` [PATCH v2 4/4] userfaultfd: remove UFFD_CLOEXEC, UFFD_NONBLOCK, and UFFD_FLAGS_SET Tal Zussman
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