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Peter Xu 5f00232112 mm: fix invalid page pointer returned with FOLL_PIN gups 
commit 7196040e19 upstream.

Patch series "mm/gup: some cleanups", v5.

This patch (of 5):

Alex reported invalid page pointer returned with pin_user_pages_remote()
from vfio after upstream commit 4b6c33b322 ("vfio/type1: Prepare for
batched pinning with struct vfio_batch").

It turns out that it's not the fault of the vfio commit; however after
vfio switches to a full page buffer to store the page pointers it starts
to expose the problem easier.

The problem is for VM_PFNMAP vmas we should normally fail with an
-EFAULT then vfio will carry on to handle the MMIO regions.  However
when the bug triggered, follow_page_mask() returned -EEXIST for such a
page, which will jump over the current page, leaving that entry in
**pages untouched.  However the caller is not aware of it, hence the
caller will reference the page as usual even if the pointer data can be
anything.

We had that -EEXIST logic since commit 1027e4436b ("mm: make GUP
handle pfn mapping unless FOLL_GET is requested") which seems very
reasonable.  It could be that when we reworked GUP with FOLL_PIN we
could have overlooked that special path in commit 3faa52c03f ("mm/gup:
track FOLL_PIN pages"), even if that commit rightfully touched up
follow_devmap_pud() on checking FOLL_PIN when it needs to return an
-EEXIST.

Attaching the Fixes to the FOLL_PIN rework commit, as it happened later
than 1027e4436b.

[jhubbard@nvidia.com: added some tags, removed a reference to an out of tree module.]

Link: https://lkml.kernel.org/r/20220207062213.235127-1-jhubbard@nvidia.com
Link: https://lkml.kernel.org/r/20220204020010.68930-1-jhubbard@nvidia.com
Link: https://lkml.kernel.org/r/20220204020010.68930-2-jhubbard@nvidia.com
Fixes: 3faa52c03f ("mm/gup: track FOLL_PIN pages")
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reported-by: Alex Williamson <alex.williamson@redhat.com>
Debugged-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: David Hildenbrand <david@redhat.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-15 20:18:53 +02:00
arch crypto: x86/poly1305 - Fixup SLS 2022-05-15 20:18:51 +02:00
block iocost: don't reset the inuse weight of under-weighted debtors 2022-05-09 09:14:31 +02:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto crypto: xts - Add softdep on ecb 2022-04-08 14:23:55 +02:00
Documentation ext4, doc: fix incorrect h_reserved size 2022-04-27 14:39:01 +02:00
drivers PCI: aardvark: Update comment about link going down after link-up 2022-05-12 12:30:34 +02:00
fs udf: Avoid using stale lengthOfImpUse 2022-05-15 20:18:52 +02:00
include rfkill: uapi: fix RFKILL_IOCTL_MAX_SIZE ioctl request definition 2022-05-15 20:18:52 +02:00
init init/main.c: return 1 from handled __setup() functions 2022-04-13 20:59:10 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-08 18:34:03 +01:00
kernel rcu: Apply callbacks processing time limit only on softirq 2022-05-12 12:30:26 +02:00
lib hex2bin: fix access beyond string end 2022-05-09 09:14:30 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: fix invalid page pointer returned with FOLL_PIN gups 2022-05-15 20:18:53 +02:00
net Bluetooth: Fix the creation of hdev->name 2022-05-15 20:18:52 +02:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-05-15 20:18:50 +02:00
scripts x86: Add straight-line-speculation mitigation 2022-05-15 20:18:51 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-08 14:23:55 +02:00
sound ASoC: soc-ops: fix error handling 2022-05-12 12:30:11 +02:00
tools objtool: Fix SLS validation for kcov tail-call replacement 2022-05-15 20:18:51 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: avoid NULL pointer dereference in kvm_dirty_ring_push 2022-04-13 20:59:26 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: adjust file entry for of_net.c after movement 2022-03-08 19:12:53 +01:00
Makefile Linux 5.15.39 2022-05-12 12:30:34 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.