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Minchan Kim a68a0262ab mm/madvise: remove racy mm ownership check
Jann spotted the security hole due to race of mm ownership check.

If the task is sharing the mm_struct but goes through execve() before
mm_access(), it could skip process_madvise_behavior_valid check.  That
makes *any advice hint* to reach into the remote process.

This patch removes the mm ownership check.  With it, it will lose the
ability that local process could give *any* advice hint with vector
interface for some reason (e.g., performance).  Since there is no
concrete example in upstream yet, it would be better to remove the
abiliity at this moment and need to review when such new advice comes
up.

Fixes: ecb8ac8b1f ("mm/madvise: introduce process_madvise() syscall: an external memory hinting API")
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-08 20:57:18 -08:00
arch Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-12-08 15:03:39 -08:00
block block-5.10-2020-12-05 2020-12-05 14:45:30 -08:00
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 Networking fixes for 5.10-rc7, including fixes from bpf, netfilter, 2020-12-03 13:10:11 -08:00
drivers Revert "scsi: megaraid_sas: Added support for shared host tagset for cpuhotplug" 2020-12-08 15:00:36 -08:00
fs afs: Fix memory leak when mounting with multiple source parameters 2020-12-08 15:59:25 -08:00
include TTY fixes for 5.10-rc7 2020-12-06 11:43:50 -08:00
init Kbuild fixes for v5.10 (2nd) 2020-12-06 10:31:39 -08:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel Fix userstacktrace option for instances 2020-12-07 11:20:26 -08:00
lib zlib: export S390 symbols for zlib modules 2020-12-06 10:19:07 -08:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/madvise: remove racy mm ownership check 2020-12-08 20:57:18 -08:00
net net/sched: act_mpls: ensure LSE is pullable before reading it 2020-12-03 11:13:37 -08:00
samples Tracing fixes for 5.10-rc6 2020-12-01 15:30:18 -08:00
scripts Kbuild fixes for v5.10 (2nd) 2020-12-06 10:31:39 -08:00
security selinux/stable-5.10 PR 20201113 2020-11-14 12:04:02 -08:00
sound ALSA: hda/realtek: Add mute LED quirk to yet another HP x360 model 2020-11-28 10:00:51 +01:00
tools A set of fixes for x86: 2020-12-06 11:22:39 -08:00
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: x86/mmu: Support dirty logging for the TDP MMU 2020-10-23 03:42:13 -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 mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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 A set of updates for the interrupt subsystem: 2020-12-06 11:15:55 -08:00
Makefile Linux 5.10-rc7 2020-12-06 14:25:12 -08:00
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.