From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, etnaviv@lists.freedesktop.org,
dri-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-media@vger.kernel.org, linux-kselftest@vger.kernel.org,
David Hildenbrand <david@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
John Hubbard <jhubbard@nvidia.com>, Peter Xu <peterx@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>, Nadav Amit <namit@vmware.com>,
Vlastimil Babka <vbabka@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
Lucas Stach <l.stach@pengutronix.de>,
David Airlie <airlied@gmail.com>,
Oded Gabbay <ogabbay@kernel.org>, Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH RFC 05/19] mm: add early FAULT_FLAG_WRITE consistency checks
Date: Mon, 7 Nov 2022 17:17:26 +0100 [thread overview]
Message-ID: <20221107161740.144456-6-david@redhat.com> (raw)
In-Reply-To: <20221107161740.144456-1-david@redhat.com>
Let's catch abuse of FAULT_FLAG_WRITE early, such that we don't have to
care in all other handlers and might get "surprises" if we forget to do
so.
Write faults without VM_MAYWRITE don't make any sense, and our
maybe_mkwrite() logic could have hidden such abuse for now.
Write faults without VM_WRITE on something that is not a COW mapping is
similarly broken, and e.g., do_wp_page() could end up placing an
anonymous page into a shared mapping, which would be bad.
This is a preparation for reliable R/O long-term pinning of pages in
private mappings, whereby we want to make sure that we will never break
COW in a read-only private mapping.
Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/memory.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c
index fe131273217a..826353da7b23 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5159,6 +5159,14 @@ static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma,
*/
if (!is_cow_mapping(vma->vm_flags))
*flags &= ~FAULT_FLAG_UNSHARE;
+ } else if (*flags & FAULT_FLAG_WRITE) {
+ /* Write faults on read-only mappings are impossible ... */
+ if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE)))
+ return VM_FAULT_SIGSEGV;
+ /* ... and FOLL_FORCE only applies to COW mappings. */
+ if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) &&
+ !is_cow_mapping(vma->vm_flags)))
+ return VM_FAULT_SIGSEGV;
}
return 0;
}
--
2.38.1
next prev parent reply other threads:[~2022-11-07 16:20 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-07 16:17 [PATCH RFC 00/19] mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O long-term pinning) David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 01/19] selftests/vm: anon_cow: prepare for non-anonymous COW tests David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 02/19] selftests/vm: cow: basic COW tests for non-anonymous pages David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 03/19] selftests/vm: cow: R/O long-term pinning reliability tests for non-anon pages David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 04/19] mm: add early FAULT_FLAG_UNSHARE consistency checks David Hildenbrand
2022-11-07 16:17 ` David Hildenbrand [this message]
2022-11-07 19:03 ` [PATCH RFC 05/19] mm: add early FAULT_FLAG_WRITE " Nadav Amit
2022-11-07 19:27 ` David Hildenbrand
2022-11-07 19:50 ` Nadav Amit
2022-11-07 16:17 ` [PATCH RFC 06/19] mm: rework handling in do_wp_page() based on private vs. shared mappings David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 07/19] mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for private mappings David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 08/19] mm: extend FAULT_FLAG_UNSHARE support to anything in a COW mapping David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 09/19] mm/gup: reliable R/O long-term pinning in COW mappings David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 10/19] RDMA/umem: remove FOLL_FORCE usage David Hildenbrand
2022-11-14 8:30 ` Leon Romanovsky
2022-11-07 16:17 ` [PATCH RFC 11/19] RDMA/usnic: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 12/19] RDMA/siw: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 13/19] media: videobuf-dma-sg: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 14/19] drm/etnaviv: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 15/19] media: pci/ivtv: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 16/19] mm/frame-vector: " David Hildenbrand
2022-11-08 4:45 ` Tomasz Figa
2022-11-08 9:40 ` David Hildenbrand
2022-11-22 12:25 ` Hans Verkuil
2022-11-22 12:38 ` David Hildenbrand
2022-11-22 14:07 ` Hans Verkuil
2022-11-22 15:03 ` David Hildenbrand
2022-11-22 17:33 ` Linus Torvalds
2022-11-07 16:17 ` [PATCH RFC 17/19] drm/exynos: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 18/19] RDMA/hw/qib/qib_user_pages: " David Hildenbrand
2022-11-07 16:17 ` [PATCH RFC 19/19] habanalabs: " David Hildenbrand
2022-11-07 21:25 ` Oded Gabbay
2022-11-07 17:27 ` [PATCH RFC 00/19] mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O long-term pinning) Linus Torvalds
2022-11-08 9:29 ` David Hildenbrand
2022-11-14 6:03 ` Christoph Hellwig
2022-11-14 8:07 ` David Hildenbrand
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