Hugh Dickins
1be7107fbe
mm: larger stack guard gap, between vmas ...
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 <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-19 21:50:20 +08:00
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2017-05-10 10:30:46 -07:00
bdi: Drop 'parent' argument from bdi_register[_va]()
2017-04-20 12:09:55 -06:00
mm/bootmem.c: cosmetic improvement of code readability
2017-02-22 16:41:29 -08:00
cma: Introduce cma_for_each_area
2017-04-18 20:41:12 +02:00
cma: Store a name in the cma structure
2017-04-18 20:41:12 +02:00
cma: Store a name in the cma structure
2017-04-18 20:41:12 +02:00
mm, compaction: finish whole pageblock to reduce fragmentation
2017-05-08 17:15:10 -07:00
mm, debug: print raw struct page data in __dump_page()
2016-12-12 18:55:08 -08:00
lib/vsprintf.c: remove %Z support
2017-02-27 18:43:47 -08:00
mm: fadvise: avoid expensive remote LRU cache draining after FADV_DONTNEED
2016-12-20 09:48:46 -08:00
Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2017-05-09 09:01:21 -07:00
treewide: use kv[mz]alloc* rather than opencoded variants
2017-05-08 17:15:13 -07:00
mm: larger stack guard gap, between vmas
2017-06-19 21:50:20 +08:00
mm: numa: avoid waiting on freed migrated pages
2017-06-17 06:37:05 +09:00
mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified
2017-06-02 15:07:38 -07:00
mm: hwpoison: call shake_page() unconditionally
2017-05-03 15:52:12 -07:00
mm, compaction: finish whole pageblock to reduce fragmentation
2017-05-08 17:15:10 -07:00
mm: remove AVR32 arch special handling in mm/Kconfig
2017-05-01 09:36:31 +02:00
mm: enable page poisoning early at boot
2017-05-03 15:52:10 -07:00
mm, thp: copying user pages must schedule on collapse
2017-05-12 15:57:16 -07:00
mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU
2017-04-18 11:42:36 -07:00
mm: fix section name for .data..ro_after_init
2017-03-31 17:13:30 -07:00
ksm: prevent crash after write_protect_page fails
2017-06-02 15:07:37 -07:00
mm/madvise: move up the behavior parameter validation
2017-05-03 15:52:11 -07:00
mm: add arch-independent testcases for RODATA
2017-02-27 18:43:48 -08:00
mm: consider memblock reservations for deferred memory initialization sizing
2017-06-02 15:07:38 -07:00
hwpoison, memcg: forcibly uncharge LRU pages
2017-05-12 15:57:15 -07:00
mm/memory-failure.c: use compound_head() flags for huge pages
2017-06-17 06:37:05 +09:00
mm: larger stack guard gap, between vmas
2017-06-19 21:50:20 +08:00
mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx
2017-05-03 15:52:09 -07:00
mm/mempolicy.c: fix error handling in set_mempolicy and mbind.
2017-04-08 10:57:55 -07:00
mm: make rmap_one boolean function
2017-05-03 15:52:10 -07:00
mm: remove shmem_mapping() shmem_zero_setup() duplicates
2017-02-24 17:46:56 -08:00
mlock: fix mlock count can not decrease in race condition
2017-06-02 15:07:38 -07:00
mm: larger stack guard gap, between vmas
2017-06-19 21:50:20 +08:00
sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>
2017-03-02 08:42:38 +01:00
mm: Use static initialization for "srcu"
2017-04-18 11:38:22 -07:00
mm/mmzone.c: swap likely to unlikely as code logic is different for next_zones_zonelist()
2017-02-22 16:41:29 -08:00
mm: convert generic code to 5-level paging
2017-03-09 11:48:47 -08:00
mm: convert generic code to 5-level paging
2017-03-09 11:48:47 -08:00
mm, vmalloc: use __GFP_HIGHMEM implicitly
2017-05-08 17:15:13 -07:00
oom: improve oom disable handling
2017-05-03 15:52:10 -07:00
Add GETFSMAP support; some performance improvements for very large
2017-05-08 11:30:05 -07:00
mm: consider memblock reservations for deferred memory initialization sizing
2017-06-02 15:07:38 -07:00
mm: enable page poisoning early at boot
2017-05-03 15:52:10 -07:00
mm: make rmap_one boolean function
2017-05-03 15:52:10 -07:00
mm, page_alloc: count movable pages when stealing from pageblock
2017-05-08 17:15:10 -07:00
mm: enable page poisoning early at boot
2017-05-03 15:52:10 -07:00
mm: fix page_vma_mapped_walk() for ksm pages
2017-04-08 00:47:48 -07:00
mm: convert generic code to 5-level paging
2017-03-09 11:48:47 -08:00
percpu: remove unused chunk_alloc parameter from pcpu_get_pages()
2017-03-06 15:56:55 -05:00
Merge branch 'sched/core' into locking/core
2017-04-04 11:31:12 +02:00
mm: convert generic code to 5-level paging
2017-03-09 11:48:47 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h>
2017-03-02 08:42:28 +01:00
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2017-05-10 10:30:46 -07:00
mm: remove rodata_test_data export, add pr_fmt
2017-05-03 15:52:09 -07:00
Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2017-03-03 11:38:56 -08:00
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2017-05-10 10:30:46 -07:00
mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU
2017-04-18 11:42:36 -07:00
mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU
2017-04-18 11:42:36 -07:00
mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU
2017-04-18 11:42:36 -07:00
slub/memcg: cure the brainless abuse of sysfs attributes
2017-06-02 15:07:37 -07:00
mm: convert generic code to 5-level paging
2017-03-09 11:48:47 -08:00
mm/sparse: refine usemap_size() a little
2017-05-03 15:52:09 -07:00
mm: move MADV_FREE pages into LRU_INACTIVE_FILE list
2017-05-03 15:52:08 -07:00
swap: cond_resched in swap_cgroup_prepare()
2017-06-17 06:37:05 +09:00
mm, swap: use kvzalloc to allocate some swap data structures
2017-05-08 17:15:13 -07:00
mm, swap: use kvzalloc to allocate some swap data structures
2017-05-08 17:15:13 -07:00
mm, swap: use kvzalloc to allocate some swap data structures
2017-05-08 17:15:13 -07:00
mm: fix data corruption due to stale mmap reads
2017-05-12 15:57:15 -07:00
mm/usercopy: Drop extra is_vmalloc_or_module() check
2017-04-05 12:30:18 -07:00
mm: convert generic code to 5-level paging
2017-03-09 11:48:47 -08:00
mm: clarify why we want kmalloc before falling backto vmallock
2017-06-02 15:07:37 -07:00
sched/headers: Prepare to move 'init_task' and 'init_thread_union' from <linux/sched.h> to <linux/sched/task.h>
2017-03-02 08:42:38 +01:00
mm, vmalloc: fix vmalloc users tracking properly
2017-05-12 15:57:15 -07:00
mm: correct the comment when reclaimed pages exceed the scanned pages
2017-06-17 06:37:05 +09:00
mm: vmscan: scan until it finds eligible pages
2017-05-12 15:57:16 -07:00
mm, vmstat: Remove spurious WARN() during zoneinfo print
2017-05-12 15:57:15 -07:00
mm: memcontrol: use node page state naming scheme for memcg
2017-05-03 15:52:11 -07:00
z3fold: fix page locking in z3fold_alloc()
2017-04-13 18:24:20 -07:00
zsmalloc: expand class bit
2017-04-13 18:24:21 -07:00
zswap: don't param_set_charp while holding spinlock
2017-02-27 18:43:45 -08:00
1be7107fbe