kernel.git/arch/tile/mm, branch linux-4.11.y

mm: larger stack guard gap, between vmas

2017-06-24T05:06:22Z

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream. Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds [wt: backport to 4.11: adjust context] Signed-off-by: Willy Tarreau Signed-off-by: Greg Kroah-Hartman

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35Z

We are going to split out of , which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:34Z

sched/headers: Prepare for new header dependencies before moving more code to

2017-03-02T07:42:30Z

We are going to split more MM APIs out of , which will have to be picked up from a couple of .c files. The APIs that we are going to move are: arch_pick_mmap_layout() arch_get_unmapped_area() arch_get_unmapped_area_topdown() mm_update_next_owner() Include the header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:29Z

userfaultfd: non-cooperative: add event for memory unmaps

2017-02-25T01:46:55Z

When a non-cooperative userfaultfd monitor copies pages in the background, it may encounter regions that were already unmapped. Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely changes in the virtual memory layout. Since there might be different uffd contexts for the affected VMAs, we first should create a temporary representation for the unmap event for each uffd context and then notify them one by one to the appropriate userfault file descriptors. The event notification occurs after the mmap_sem has been released. [arnd@arndb.de: fix nommu build] Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de [mhocko@suse.com: fix nommu build] Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Signed-off-by: Michal Hocko Signed-off-by: Arnd Bergmann Acked-by: Hillf Danton Cc: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Mike Kravetz Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

arch, mm: remove arch specific show_mem

2017-02-23T00:41:30Z

We have a generic implementation for quite some time already. If there is any arch specific information to be printed then we should add a callback called from the generic code rather than duplicate the whole show_mem. The current code has resulted in the code duplication and the output divergence which is both confusing and adds maintainance costs. Let's just get rid of this mess. Link: http://lkml.kernel.org/r/20170117091543.25850-4-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Guan Xuetao [UniCore32] Acked-by: Helge Deller [for parisc] Acked-by: Chris Metcalf [for tile] Acked-by: Mel Gorman Acked-by: Johannes Weiner Cc: Tony Luck Cc: Fenghua Yu Cc: "James E.J. Bottomley" Cc: "David S. Miller" Cc: Hillf Danton Cc: Vlastimil Babka Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

tile: use __ro_after_init instead of tile-specific __write_once

2016-12-16T20:32:29Z

The semantics of the old tile __write_once are the same as the newer generic __ro_after_init, so rename them all and get rid of the tile-specific version. This does not enable actual support for __ro_after_init, which had been dropped from the tile architecture before the initial upstreaming was done, since we had at that time switched to using 16MB huge pages to map the kernel. Signed-off-by: Chris Metcalf

tile: migrate exception table users off module.h and onto extable.h

2016-12-16T20:32:29Z

These files were only including module.h for exception table related functions. We've now separated that content out into its own file "extable.h" so now move over to that and avoid all the extra header content in module.h that we don't really need to compile these files. Cc: Chris Metcalf Signed-off-by: Paul Gortmaker Signed-off-by: Chris Metcalf

tile: use simpler API for random address requests

2016-10-11T22:06:32Z

Currently, all callers to randomize_range() set the length to 0 and calculate end by adding a constant to the start address. We can simplify the API to remove a bunch of needless checks and variables. Use the new randomize_addr(start, range) call to set the requested address. Link: http://lkml.kernel.org/r/20160803233913.32511-6-jason@lakedaemon.net Signed-off-by: Jason Cooper Acked-by: Kees Cook Cc: "Theodore Ts'o" Cc: Chris Metcalf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds