Davidlohr Bueso 67dd0bad81 Revert "ipc/shm: Fix shmat mmap nil-page protection" ... commit a73ab244f0 upstream. Patch series "ipc/shm: shmat() fixes around nil-page". These patches fix two issues reported[1] a while back by Joe and Andrea around how shmat(2) behaves with nil-page. The first reverts a commit that it was incorrectly thought that mapping nil-page (address=0) was a no no with MAP_FIXED. This is not the case, with the exception of SHM_REMAP; which is address in the second patch. I chose two patches because it is easier to backport and it explicitly reverts bogus behaviour. Both patches ought to be in -stable and ltp testcases need updated (the added testcase around the cve can be modified to just test for SHM_RND|SHM_REMAP). [1] lkml.kernel.org/r/20180430172152.nfa564pvgpk3ut7p@linux-n805 This patch (of 2): Commit 95e91b831f ("ipc/shm: Fix shmat mmap nil-page protection") worked on the idea that we should not be mapping as root addr=0 and MAP_FIXED. However, it was reported that this scenario is in fact valid, thus making the patch both bogus and breaks userspace as well. For example X11's libint10.so relies on shmat(1, SHM_RND) for lowmem initialization[1]. [1] https://cgit.freedesktop.org/xorg/xserver/tree/hw/xfree86/os-support/linux/int10/linux.c#n347 Link: http://lkml.kernel.org/r/20180503203243.15045-2-dave@stgolabs.net Fixes: 95e91b831f ("ipc/shm: Fix shmat mmap nil-page protection") Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Joe Lawrence <joe.lawrence@redhat.com> Reported-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Manfred Spraul <manfred@colorfullife.com> 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>		2018-05-30 07:51:49 +02:00
..
compat.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
ipc_sysctl.c	ipc/msg: increase MSGMNI, remove scaling	2014-12-13 12:42:52 -08:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
mq_sysctl.c
mqueue.c	ipc: mqueue: Replace timespec with timespec64	2017-09-03 20:21:24 -04:00
msg.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
msgutil.c	ipc: convert ipc_namespace.count from atomic_t to refcount_t	2017-09-08 18:26:51 -07:00
namespace.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
sem.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
shm.c	Revert "ipc/shm: Fix shmat mmap nil-page protection"	2018-05-30 07:51:49 +02:00
syscall.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
util.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
util.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00