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Michael S. Tsirkin aa70aeaf04 get_user_pages_fast(): return -EFAULT on access_ok failure 
commit c61611f709 upstream.

get_user_pages_fast is supposed to be a faster drop-in equivalent of
get_user_pages.  As such, callers expect it to return a negative return
code when passed an invalid address, and never expect it to return 0
when passed a positive number of pages, since its documentation says:

 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno.

When get_user_pages_fast fall back on get_user_pages this is exactly
what happens.  Unfortunately the implementation is inconsistent: it
returns 0 if passed a kernel address, confusing callers: for example,
the following is pretty common but does not appear to do the right thing
with a kernel address:

        ret = get_user_pages_fast(addr, 1, writeable, &page);
        if (ret < 0)
                return ret;

Change get_user_pages_fast to return -EFAULT when supplied a kernel
address to make it match expectations.

All callers have been audited for consistency with the documented
semantics.

Link: http://lkml.kernel.org/r/1522962072-182137-4-git-send-email-mst@redhat.com
Fixes: 5b65c4677a ("mm, x86/mm: Fix performance regression in get_user_pages_fast()")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: syzbot+6304bf97ef436580fede@syzkaller.appspotmail.com
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: <stable@vger.kernel.org>
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>
History 2018-04-19 08:54:11 +02:00
arch s390/compat: fix setup_frame32 2018-04-19 08:54:11 +02:00
block blk-mq: don't keep offline CPUs mapped to hctx 0 2018-04-19 08:54:09 +02:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto crypto: ahash - Fix early termination in hash walk 2018-04-08 14:29:50 +02:00
Documentation serial: 8250: Add Nuvoton NPCM UART 2018-04-08 14:29:49 +02:00
drivers s390/qdio: don't merge ERROR output buffers 2018-04-19 08:54:11 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs nfsd: fix incorrect umasks 2018-04-19 08:54:10 +02:00
include media: v4l2-core: fix size of devnode_nums[] bitarray 2018-04-19 08:54:05 +02:00
init jump_label: Disable jump labels in __exit code 2018-03-20 08:57:17 +01:00
ipc ipc/shm.c: add split function to shm_vm_ops 2018-03-28 13:42:05 -10:00
kernel perf/core: Fix use-after-free in uprobe_perf_close() 2018-04-19 08:54:07 +02:00
lib lib: fix stall in __bitmap_parselist() 2018-04-19 08:54:08 +02:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm get_user_pages_fast(): return -EFAULT on access_ok failure 2018-04-19 08:54:11 +02:00
net sunrpc: remove incorrect HMAC request initialization 2018-04-19 08:54:08 +02:00
samples - do not build samples when cross compiling (Michal Hocko) 2018-02-27 10:39:29 -08:00
scripts kbuild: rpm-pkg: Support GNU tar >= 1.29 2018-03-28 01:42:17 +09:00
security apparmor: fix resource audit messages when auditing peer 2018-04-19 08:54:10 +02:00
sound ALSA: pcm: potential uninitialized return values 2018-03-27 15:20:19 +02:00
tools perf intel-pt: Fix timestamp following overflow 2018-04-19 08:54:07 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt kvm/arm fixes for 4.16, take 2 2018-03-15 21:45:37 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: ignore ASN.1 auto generated files 2018-02-14 21:05:38 +01:00
.mailmap mailmap: Update email address for Gregory CLEMENT 2018-03-09 17:48:50 +01:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2018-03-28 14:34:55 -10:00
Makefile Linux 4.16.2 2018-04-12 12:30:01 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.