kernel.git/arch/s390, branch linux-4.11.y

s390: reduce ELF_ET_DYN_BASE

2017-07-21T05:00:12Z

commit a73dc5370e153ac63718d850bddf0c9aa9d871e6 upstream. Now that explicitly executed loaders are loaded in the mmap region, we have more freedom to decide where we position PIE binaries in the address space to avoid possible collisions with mmap or stack regions. For 64-bit, align to 4GB to allow runtimes to use the entire 32-bit address space for 32-bit pointers. On 32-bit use 4MB, which is the traditional x86 minimum load location, likely to avoid historically requiring a 4MB page table entry when only a portion of the first 4MB would be used (since the NULL address is avoided). For s390 the position could be 0x10000, but that is needlessly close to the NULL address. Link: http://lkml.kernel.org/r/1498154792-49952-5-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: James Hogan Cc: Pratyush Anand Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

KVM: s390: gaccess: fix real-space designation asce handling for gmap shadows

2017-06-29T11:02:47Z

commit addb63c18a0d52a9ce2611d039f981f7b6148d2b upstream. For real-space designation asces the asce origin part is only a token. The asce token origin must not be used to generate an effective address for storage references. This however is erroneously done within kvm_s390_shadow_tables(). Furthermore within the same function the wrong parts of virtual addresses are used to generate a corresponding real address (e.g. the region second index is used as region first index). Both of the above can result in incorrect address translations. Only for real space designations with a token origin of zero and addresses below one megabyte the translation was correct. Furthermore replace a "!asce.r" statement with a "!*fake" statement to make it more obvious that a specific condition has nothing to do with the architecture, but with the fake handling of real space designations. Fixes: 3218f7094b6b ("s390/mm: support real-space for gmap shadows") Cc: David Hildenbrand Signed-off-by: Heiko Carstens Reviewed-by: Martin Schwidefsky Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman

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

s390/kvm: do not rely on the ILC on kvm host protection fauls

2017-06-17T04:44:18Z

commit c0e7bb38c07cbd8269549ee0a0566021a3c729de upstream. For most cases a protection exception in the host (e.g. copy on write or dirty tracking) on the sie instruction will indicate an instruction length of 4. Turns out that there are some corner cases (e.g. runtime instrumentation) where this is not necessarily true and the ILC is unpredictable. Let's replace our 4 byte rewind_pad with 3 byte nops to prepare for all possible ILCs. Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/cputime: fix incorrect system time

2017-05-25T13:46:14Z

commit 07a63cbe8bcb6ba72fb989dcab1ec55ec6c36c7e upstream. git commit c5328901aa1db134 "[S390] entry[64].S improvements" removed the update of the exit_timer lowcore field from the critical section cleanup of the .Lsysc_restore/.Lsysc_done and .Lio_restore/.Lio_done blocks. If the PSW is updated by the critical section cleanup to point to user space again, the interrupt entry code will do a vtime calculation after the cleanup completed with an exit_timer value which has *not* been updated. Due to this incorrect system time deltas are calculated. If an interrupt occured with an old PSW between .Lsysc_restore/.Lsysc_done or .Lio_restore/.Lio_done update __LC_EXIT_TIMER with the system entry time of the interrupt. Tested-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/kdump: Add final note

2017-05-25T13:46:14Z

commit dcc00b79fc3d076832f7240de8870f492629b171 upstream. Since linux v3.14 with commit 38dfac843cb6d7be1 ("vmcore: prevent PT_NOTE p_memsz overflow during header update") on s390 we get the following message in the kdump kernel: Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x6b6b6b6b, n_descsz=0x6b6b6b6b The reason for this is that we don't create a final zero note in the ELF header which the proc/vmcore code uses to find out the end of the notes section (see also kernel/kexec_core.c:final_note()). It still worked on s390 by chance because we (most of the time?) have the byte pattern 0x6b6b6b6b after the notes section which also makes the notes parsing code stop in update_note_header_size_elf64() because 0x6b6b6b6b is interpreded as note size: if ((real_sz + sz) > max_sz) { pr_warn("Warning: Exceeded p_memsz, dropping P ...); break; } So fix this and add the missing final note to the ELF header. We don't have to adjust the memory size for ELF header ("alloc_size") because the new ELF note still fits into the 0x1000 base memory. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/mm: fix CMMA vs KSM vs others

2017-04-12T05:40:24Z

On heavy paging with KSM I see guest data corruption. Turns out that KSM will add pages to its tree, where the mapping return true for pte_unused (or might become as such later). KSM will unmap such pages and reinstantiate with different attributes (e.g. write protected or special, e.g. in replace_page or write_protect_page)). This uncovered a bug in our pagetable handling: We must remove the unused flag as soon as an entry becomes present again. Cc: stable@vger.kernel.org Signed-of-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2017-04-08T08:39:43Z

Pull KVM fixes from Radim Krčmář: "ARM: - Fix a problem with GICv3 userspace save/restore - Clarify GICv2 userspace save/restore ABI - Be more careful in clearing GIC LRs - Add missing synchronization primitive to our MMU handling code PPC: - Check for a NULL return from kzalloc s390: - Prevent translation exception errors on valid page tables for the instruction-exection-protection support x86: - Fix Page-Modification Logging when running a nested guest" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: PPC: Book3S HV: Check for kmalloc errors in ioctl KVM: nVMX: initialize PML fields in vmcs02 KVM: nVMX: do not leak PML full vmexit to L1 KVM: arm/arm64: vgic: Fix GICC_PMR uaccess on GICv3 and clarify ABI KVM: arm64: Ensure LRs are clear when they should be kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd KVM: s390: remove change-recording override support arm/arm64: KVM: Take mmap_sem in kvm_arch_prepare_memory_region arm/arm64: KVM: Take mmap_sem in stage2_unmap_vm

Merge tag 'kvm-s390-master-4.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux

2017-04-04T12:42:51Z

From: Christian Borntraeger KVM: s390: Fix instruction-execution-protection/change-recording override This is a fix that prevents translation exception errors on valid page tables for the instruction-exection-protection support. This feature was added during the 4.11 merge window. We have to remove an old check that would trigger if the change-recording override is not available (e.g. edat1 disabled via cpu model).

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2017-04-03T15:44:43Z

Pull s390 fixes from Martin Schwidefsky: "Four bug fixes, two of them for stable: - avoid initrd corruptions in the kernel decompressor - prevent inconsistent dumps if the boot CPU does not have address zero - fix the new pkey interface added with the merge window for 4.11 - a fix for a fix, another issue with user copy zero padding" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/uaccess: get_user() should zero on failure (again) s390/pkey: Fix wrong handling of secure key with old MKVP s390/smp: fix ipl from cpu with non-zero address s390/decompressor: fix initrd corruption caused by bss clear