From: David Hildenbrand <david@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
stable@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Peter Xu <peterx@redhat.com>, Hugh Dickins <hughd@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>,
John Hubbard <jhubbard@nvidia.com>,
Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH v1] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW
Date: Tue, 9 Aug 2022 22:23:49 +0200 [thread overview]
Message-ID: <915e2f40-b94a-cef4-7aa7-a402e93dae68@redhat.com> (raw)
In-Reply-To: <CAHk-=wgYAy5ho0Wqx+eri_+a5apYU1Th826UScE7rZRiyhPcGA@mail.gmail.com>
On 09.08.22 22:20, Linus Torvalds wrote:
> On Tue, Aug 9, 2022 at 1:14 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> But as there are two bits, I'm sure somebody ends up touching one and
>> not the other.
>
> Ugh. The nommu code certainly does odd things here. That just looks wrong.
>
> And the hugetlb code does something horrible too, but never *sets* it,
> so it looks like some odd subset of VM_SHARED.
mm/mmap.c:do_mmap() contains the magic bit
switch (flags & MAP_TYPE) {
case MAP_SHARED:
...
case MAP_SHARED_VALIDATE:
...
vm_flags |= VM_SHARED | VM_MAYSHARE;
if (!(file->f_mode & FMODE_WRITE))
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
fallthrough;
VM_SHARED semantics are confusing.
--
Thanks,
David / dhildenb
prev parent reply other threads:[~2022-08-09 20:23 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-08 7:32 [PATCH v1] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW David Hildenbrand
2022-08-08 16:02 ` David Hildenbrand
2022-08-09 18:27 ` Linus Torvalds
2022-08-09 18:45 ` David Hildenbrand
2022-08-09 18:59 ` Linus Torvalds
2022-08-09 19:07 ` Jason Gunthorpe
2022-08-09 19:21 ` Linus Torvalds
2022-08-09 21:16 ` David Laight
2022-08-11 7:13 ` [PATCH] sched/all: Change BUG_ON() instances to WARN_ON() Ingo Molnar
2022-08-11 20:43 ` Linus Torvalds
2022-08-11 21:28 ` Matthew Wilcox
2022-08-11 23:22 ` Jason Gunthorpe
2022-08-14 1:10 ` John Hubbard
2022-08-12 9:29 ` [PATCH v2] sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE() Ingo Molnar
[not found] ` <20220815144143.zjsiamw5y22bvgki@suse.de>
2022-08-15 22:12 ` John Hubbard
2022-08-21 11:28 ` Ingo Molnar
2022-08-09 18:40 ` [PATCH v1] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW Linus Torvalds
2022-08-09 18:48 ` Jason Gunthorpe
2022-08-09 18:53 ` David Hildenbrand
2022-08-09 19:07 ` Linus Torvalds
2022-08-09 19:20 ` David Hildenbrand
2022-08-09 18:48 ` Linus Torvalds
2022-08-09 19:09 ` David Hildenbrand
2022-08-09 20:00 ` Linus Torvalds
2022-08-09 20:06 ` David Hildenbrand
2022-08-09 20:07 ` David Hildenbrand
2022-08-09 20:14 ` Linus Torvalds
2022-08-09 20:20 ` David Hildenbrand
2022-08-09 20:30 ` Linus Torvalds
2022-08-09 20:38 ` Linus Torvalds
2022-08-09 20:42 ` David Hildenbrand
2022-08-09 20:20 ` Linus Torvalds
2022-08-09 20:23 ` David Hildenbrand [this message]
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