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Jann Horn b2767d97f5 binfmt_elf: take the mmap lock around find_extend_vma()
create_elf_tables() runs after setup_new_exec(), so other tasks can
already access our new mm and do things like process_madvise() on it.  (At
the time I'm writing this commit, process_madvise() is not in mainline
yet, but has been in akpm's tree for some time.)

While I believe that there are currently no APIs that would actually allow
another process to mess up our VMA tree (process_madvise() is limited to
MADV_COLD and MADV_PAGEOUT, and uring and userfaultfd cannot reach an mm
under which no syscalls have been executed yet), this seems like an
accident waiting to happen.

Let's make sure that we always take the mmap lock around GUP paths as long
as another process might be able to see the mm.

(Yes, this diff looks suspicious because we drop the lock before doing
anything with `vma`, but that's because we actually don't do anything with
it apart from the NULL check.)

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michel Lespinasse <walken@google.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Link: https://lkml.kernel.org/r/CAG48ez1-PBCdv3y8pn-Ty-b+FmBSLwDuVKFSt8h7wARLy0dF-Q@mail.gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-18 09:27:09 -07:00
arch ia64: fix build error with !COREDUMP 2020-10-18 09:27:09 -07:00
block docs: bio: fix a kerneldoc markup 2020-10-15 07:49:48 +02:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
Documentation RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
drivers RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
fs binfmt_elf: take the mmap lock around find_extend_vma() 2020-10-18 09:27:09 -07:00
include mm: kmem: enable kernel memcg accounting from interrupt contexts 2020-10-18 09:27:09 -07:00
init networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel docs updates for v5.10-rc1 2020-10-16 15:02:21 -07:00
lib RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/gup_benchmark: take the mmap lock around GUP 2020-10-18 09:27:09 -07:00
net networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
samples networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
scripts docs updates for v5.10-rc1 2020-10-16 15:02:21 -07:00
security networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
sound dma-mapping updates for 5.10 2020-10-15 14:43:29 -07:00
tools perf tools changes for v5.10: 1st batch 2020-10-17 11:47:46 -07:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: fix memory leak in kvm_io_bus_unregister_dev() 2020-09-11 13:15:11 -04:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: jarkko.sakkinen@linux.intel.com -> jarkko@kernel.org 2020-10-16 11:11:19 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
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 RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
Makefile networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.