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* mm: larger stack guard gap, between vmasHugh Dickins2017-06-191-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* sched/headers: Prepare for new header dependencies before moving more code ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | | | | to <linux/sched/mm.h> We are going to split more MM APIs out of <linux/sched.h>, 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 <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'akpm' (Andrew's patchbomb)Linus Torvalds2012-12-111-114/+23
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge misc updates from Andrew Morton: "About half of most of MM. Going very early this time due to uncertainty over the coreautounifiednumasched things. I'll send the other half of most of MM tomorrow. The rest of MM awaits a slab merge from Pekka." * emailed patches from Andrew Morton: (71 commits) memory_hotplug: ensure every online node has NORMAL memory memory_hotplug: handle empty zone when online_movable/online_kernel mm, memory-hotplug: dynamic configure movable memory and portion memory drivers/base/node.c: cleanup node_state_attr[] bootmem: fix wrong call parameter for free_bootmem() avr32, kconfig: remove HAVE_ARCH_BOOTMEM mm: cma: remove watermark hacks mm: cma: skip watermarks check for already isolated blocks in split_free_page() mm, oom: fix race when specifying a thread as the oom origin mm, oom: change type of oom_score_adj to short mm: cleanup register_node() mm, mempolicy: remove duplicate code mm/vmscan.c: try_to_freeze() returns boolean mm: introduce putback_movable_pages() virtio_balloon: introduce migration primitives to balloon pages mm: introduce compaction and migration for ballooned pages mm: introduce a common interface for balloon pages mobility mm: redefine address_space.assoc_mapping mm: adjust address_space_operations.migratepage() return code arch/sparc/kernel/sys_sparc_64.c: s/COLOUR/COLOR/ ...
| * mm: use vm_unmapped_area() on sh architectureMichel Lespinasse2012-12-111-114/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Update the sh arch_get_unmapped_area[_topdown] functions to make use of vm_unmapped_area() instead of implementing a brute force search. [akpm@linux-foundation.org: remove now-unused COLOUR_ALIGN_DOWN()] Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | /dev/mem: use phys_addr_t for physical addressesCyril Chemparathy2012-10-241-1/+1
|/ | | | | | | | | This patch fixes the /dev/mem driver to use phys_addr_t for physical addresses. This is required on PAE systems, especially those that run entirely out of >4G physical memory space. Signed-off-by: Cyril Chemparathy <cyril@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fix broken aliasing checks for MAP_FIXED on sparc32, mips, arm and shAl Viro2009-12-111-1/+2
| | | | | | | | We want addr - (pgoff << PAGE_SHIFT) consistently coloured... Acked-by: Paul Mundt <lethal@linux-sh.org> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* sh: rework nommu for generic cache.c use.Paul Mundt2009-08-151-1/+1
| | | | | | | This does a bit of reorganizing for allowing nommu to use the new and generic cache.c, no functional changes. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* sh: Handle shm_align_mask also for HAVE_ARCH_UNMAPPED_AREA_TOPDOWN.Paul Mundt2009-05-071-4/+132
| | | | | | | Presently shm_align_mask is only looked at for the bottom up case, but we still want this for proper colouring constraints in the topdown case. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* sh: Move arch_get_unmapped_area() in to arch/sh/mm/mmap.c.Paul Mundt2008-12-221-0/+94
| | | | | | | Now that arch/sh/mm/mmap.c exists, move arch_get_unmapped_area() there. Follows the ARM change. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* sh: Don't factor in PAGE_OFFSET for valid_phys_addr_range() check.Paul Mundt2008-11-131-1/+1
| | | | Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* sh: Provide a sane valid_phys_addr_range() to prevent TLB reset with PMB.Paul Mundt2008-11-121-0/+31
With the PMB enabled, only P1SEG and up are covered by the PMB mappings, meaning that situations where out-of-bounds physical addresses are read from will lead to TLB reset after the PMB miss, allowing for use cases like dd if=/dev/mem to reset the TLB. Fix this up to make sure the reference is between __MEMORY_START (phys) and __pa(high_memory). This is coherent across all variants of sh/sh64 with and without MMU, though the PMB bug itself is only applicable to SH-4A parts. Reported-by: Hideo Saito <saito@densan.co.jp> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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