From: Andrew Morton <akpm@linux-foundation.org>
To: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: linux-mm@kvack.org, Suren Baghdasaryan <surenb@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
sidhartha.kumar@oracle.com,
"Paul E . McKenney" <paulmck@kernel.org>,
Bert Karwatzki <spasswolf@web.de>, Jiri Olsa <olsajiri@gmail.com>,
linux-kernel@vger.kernel.org, Kees Cook <kees@kernel.org>
Subject: Re: [PATCH v2 00/15] Avoid MAP_FIXED gap exposure
Date: Wed, 26 Jun 2024 13:58:55 -0700 [thread overview]
Message-ID: <20240626135855.a4b64612a9104ff163e30bd7@linux-foundation.org> (raw)
In-Reply-To: <20240625191145.3382793-1-Liam.Howlett@oracle.com>
On Tue, 25 Jun 2024 15:11:30 -0400 "Liam R. Howlett" <Liam.Howlett@oracle.com> wrote:
> It is now possible to walk the vma tree using the rcu read locks and is
> beneficial to do so to reduce lock contention. Doing so while a
> MAP_FIXED mapping is executing means that a reader may see a gap in the
> vma tree that should never logically exist - and does not when using the
> mmap lock in read mode. The temporal gap exists because mmap_region()
> calls munmap() prior to installing the new mapping.
What are the consequences when this race hits? IOW, why do we need to
change anything?
next prev parent reply other threads:[~2024-06-26 20:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-25 19:11 Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 01/15] mm/mmap: Correctly position vma_iterator in __split_vma() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 02/15] mm/mmap: Introduce abort_munmap_vmas() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 03/15] mm/mmap: Introduce vmi_complete_munmap_vmas() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 04/15] mm/mmap: Extract the gathering of vmas from do_vmi_align_munmap() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 05/15] mm/mmap: Introduce vma_munmap_struct for use in munmap operations Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 06/15] mm/mmap: Change munmap to use vma_munmap_struct() for accounting and surrounding vmas Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 07/15] mm/mmap: Extract validate_mm() from vma_complete() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 08/15] mm/mmap: Inline munmap operation in mmap_region() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 09/15] mm/mmap: Expand mmap_region() munmap call Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 10/15] mm/mmap: Reposition vma iterator in mmap_region() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 11/15] mm/mmap: Track start and end of munmap in vma_munmap_struct Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 12/15] mm/mmap: Avoid zeroing vma tree in mmap_region() Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 13/15] mm/mmap: Use PHYS_PFN " Liam R. Howlett
2024-06-25 19:11 ` [PATCH v2 14/15] mm/mmap: Use vms accounted pages " Liam R. Howlett
2024-06-26 16:32 ` Kees Cook
2024-06-26 18:04 ` Liam R. Howlett
2024-06-26 18:45 ` Kees Cook
2024-06-25 19:11 ` [PATCH v2 15/15] mm/mmap: Move may_expand_vm() check " Liam R. Howlett
2024-06-26 20:58 ` Andrew Morton [this message]
2024-06-27 1:15 ` [PATCH v2 00/15] Avoid MAP_FIXED gap exposure Liam R. Howlett
2024-06-27 1:28 ` Andrew Morton
2024-06-27 13:31 ` Liam R. Howlett
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