kernel/linux.git/mm, branch v4.17.15

x86/speculation/l1tf: Limit swap file size to MAX_PA/2

2018-08-15T16:11:00+00:00

commit 377eeaa8e11fe815b1d07c81c4a0e2843a8c15eb upstream For the L1TF workaround its necessary to limit the swap file size to below MAX_PA/2, so that the higher bits of the swap offset inverted never point to valid memory. Add a mechanism for the architecture to override the swap file size check in swapfile.c and add a x86 specific max swapfile check function that enforces that limit. The check is only enabled if the CPU is vulnerable to L1TF. In VMs with 42bit MAX_PA the typical limit is 2TB now, on a native system with 46bit PA it is 32TB. The limit is only per individual swap file, so it's always possible to exceed these limits with multiple swap files or partitions. Signed-off-by: Andi Kleen Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf Acked-by: Michal Hocko Acked-by: Dave Hansen Signed-off-by: Greg Kroah-Hartman

x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings

2018-08-15T16:10:59+00:00

commit 42e4089c7890725fcd329999252dc489b72f2921 upstream For L1TF PROT_NONE mappings are protected by inverting the PFN in the page table entry. This sets the high bits in the CPU's address space, thus making sure to point to not point an unmapped entry to valid cached memory. Some server system BIOSes put the MMIO mappings high up in the physical address space. If such an high mapping was mapped to unprivileged users they could attack low memory by setting such a mapping to PROT_NONE. This could happen through a special device driver which is not access protected. Normal /dev/mem is of course access protected. To avoid this forbid PROT_NONE mappings or mprotect for high MMIO mappings. Valid page mappings are allowed because the system is then unsafe anyways. It's not expected that users commonly use PROT_NONE on MMIO. But to minimize any impact this is only enforced if the mapping actually refers to a high MMIO address (defined as the MAX_PA-1 bit being set), and also skip the check for root. For mmaps this is straight forward and can be handled in vm_insert_pfn and in remap_pfn_range(). For mprotect it's a bit trickier. At the point where the actual PTEs are accessed a lot of state has been changed and it would be difficult to undo on an error. Since this is a uncommon case use a separate early page talk walk pass for MMIO PROT_NONE mappings that checks for this condition early. For non MMIO and non PROT_NONE there are no changes. Signed-off-by: Andi Kleen Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf Acked-by: Dave Hansen Signed-off-by: Greg Kroah-Hartman

ipc/shm.c add ->pagesize function to shm_vm_ops

2018-08-06T14:18:21+00:00

commit eec3636ad198d4ac61e574cb122cb67e9bef5492 upstream. Commit 05ea88608d4e ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") adds a new ->pagesize() function to hugetlb_vm_ops, intended to cover all hugetlbfs backed files. With System V shared memory model, if "huge page" is specified, the "shared memory" is backed by hugetlbfs files, but the mappings initiated via shmget/shmat have their original vm_ops overwritten with shm_vm_ops, so we need to add a ->pagesize function to shm_vm_ops. Otherwise, vma_kernel_pagesize() returns PAGE_SIZE given a hugetlbfs backed vma, result in below BUG: fs/hugetlbfs/inode.c 443 if (unlikely(page_mapped(page))) { 444 BUG_ON(truncate_op); resulting in hugetlbfs: oracle (4592): Using mlock ulimits for SHM_HUGETLB is deprecated ------------[ cut here ]------------ kernel BUG at fs/hugetlbfs/inode.c:444! Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 ... CPU: 35 PID: 5583 Comm: oracle_5583_sbt Not tainted 4.14.35-1829.el7uek.x86_64 #2 RIP: 0010:remove_inode_hugepages+0x3db/0x3e2 .... Call Trace: hugetlbfs_evict_inode+0x1e/0x3e evict+0xdb/0x1af iput+0x1a2/0x1f7 dentry_unlink_inode+0xc6/0xf0 __dentry_kill+0xd8/0x18d dput+0x1b5/0x1ed __fput+0x18b/0x216 ____fput+0xe/0x10 task_work_run+0x90/0xa7 exit_to_usermode_loop+0xdd/0x116 do_syscall_64+0x187/0x1ae entry_SYSCALL_64_after_hwframe+0x150/0x0 [jane.chu@oracle.com: relocate comment] Link: http://lkml.kernel.org/r/20180731044831.26036-1-jane.chu@oracle.com Link: http://lkml.kernel.org/r/20180727211727.5020-1-jane.chu@oracle.com Fixes: 05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") Signed-off-by: Jane Chu Suggested-by: Mike Kravetz Reviewed-by: Mike Kravetz Acked-by: Davidlohr Bueso Acked-by: Michal Hocko Cc: Dan Williams Cc: Jan Kara Cc: Jérôme Glisse Cc: Manfred Spraul Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/slub.c: add __printf verification to slab_err()

2018-08-03T05:47:35+00:00

[ Upstream commit a38965bf941b7c2af50de09c96bc5f03e136caef ] __printf is useful to verify format and arguments. Remove the following warning (with W=1): mm/slub.c:721:2: warning: function might be possible candidate for `gnu_printf' format attribute [-Wsuggest-attribute=format] Link: http://lkml.kernel.org/r/20180505200706.19986-1-malat@debian.org Signed-off-by: Mathieu Malaterre Reviewed-by: Andrew Morton Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm: vmalloc: avoid racy handling of debugobjects in vunmap

2018-08-03T05:47:35+00:00

[ Upstream commit f3c01d2f3ade6790db67f80fef60df84424f8964 ] Currently, __vunmap flow is, 1) Release the VM area 2) Free the debug objects corresponding to that vm area. This leave some race window open. 1) Release the VM area 1.5) Some other client gets the same vm area 1.6) This client allocates new debug objects on the same vm area 2) Free the debug objects corresponding to this vm area. Here, we actually free 'other' client's debug objects. Fix this by freeing the debug objects first and then releasing the VM area. Link: http://lkml.kernel.org/r/1523961828-9485-2-git-send-email-cpandya@codeaurora.org Signed-off-by: Chintan Pandya Reviewed-by: Andrew Morton Cc: Ard Biesheuvel Cc: Byungchul Park Cc: Catalin Marinas Cc: Florian Fainelli Cc: Johannes Weiner Cc: Laura Abbott Cc: Vlastimil Babka Cc: Wei Yang Cc: Yisheng Xie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm/huge_memory.c: fix data loss when splitting a file pmd

2018-07-25T09:26:08+00:00

commit e1f1b1572e8db87a56609fd05bef76f98f0e456a upstream. __split_huge_pmd_locked() must check if the cleared huge pmd was dirty, and propagate that to PageDirty: otherwise, data may be lost when a huge tmpfs page is modified then split then reclaimed. How has this taken so long to be noticed? Because there was no problem when the huge page is written by a write system call (shmem_write_end() calls set_page_dirty()), nor when the page is allocated for a write fault (fault_dirty_shared_page() calls set_page_dirty()); but when allocated for a read fault (which MAP_POPULATE simulates), no set_page_dirty(). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1807111741430.1106@eggly.anvils Fixes: d21b9e57c74c ("thp: handle file pages in split_huge_pmd()") Signed-off-by: Hugh Dickins Reported-by: Ashwin Chaugule Reviewed-by: Yang Shi Reviewed-by: Kirill A. Shutemov Cc: "Huang, Ying" Cc: [4.8+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: memcg: fix use after free in mem_cgroup_iter()

2018-07-25T09:26:08+00:00

commit 9f15bde671355c351cf20d9f879004b234353100 upstream. It was reported that a kernel crash happened in mem_cgroup_iter(), which can be triggered if the legacy cgroup-v1 non-hierarchical mode is used. Unable to handle kernel paging request at virtual address 6b6b6b6b6b6b8f ...... Call trace: mem_cgroup_iter+0x2e0/0x6d4 shrink_zone+0x8c/0x324 balance_pgdat+0x450/0x640 kswapd+0x130/0x4b8 kthread+0xe8/0xfc ret_from_fork+0x10/0x20 mem_cgroup_iter(): ...... if (css_tryget(css)) <-- crash here break; ...... The crashing reason is that mem_cgroup_iter() uses the memcg object whose pointer is stored in iter->position, which has been freed before and filled with POISON_FREE(0x6b). And the root cause of the use-after-free issue is that invalidate_reclaim_iterators() fails to reset the value of iter->position to NULL when the css of the memcg is released in non- hierarchical mode. Link: http://lkml.kernel.org/r/1531994807-25639-1-git-send-email-jing.xia@unisoc.com Fixes: 6df38689e0e9 ("mm: memcontrol: fix possible memcg leak due to interrupted reclaim") Signed-off-by: Jing Xia Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Vladimir Davydov Cc: Cc: Shakeel Butt Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

bdi: Fix another oops in wb_workfn()

2018-07-22T13:16:06+00:00

commit 3ee7e8697d5860b173132606d80a9cd35e7113ee upstream. syzbot is reporting NULL pointer dereference at wb_workfn() [1] due to wb->bdi->dev being NULL. And Dmitry confirmed that wb->state was WB_shutting_down after wb->bdi->dev became NULL. This indicates that unregister_bdi() failed to call wb_shutdown() on one of wb objects. The problem is in cgwb_bdi_unregister() which does cgwb_kill() and thus drops bdi's reference to wb structures before going through the list of wbs again and calling wb_shutdown() on each of them. This way the loop iterating through all wbs can easily miss a wb if that wb has already passed through cgwb_remove_from_bdi_list() called from wb_shutdown() from cgwb_release_workfn() and as a result fully shutdown bdi although wb_workfn() for this wb structure is still running. In fact there are also other ways cgwb_bdi_unregister() can race with cgwb_release_workfn() leading e.g. to use-after-free issues: CPU1 CPU2 cgwb_bdi_unregister() cgwb_kill(*slot); cgwb_release() queue_work(cgwb_release_wq, &wb->release_work); cgwb_release_workfn() wb = list_first_entry(&bdi->wb_list, ...) spin_unlock_irq(&cgwb_lock); wb_shutdown(wb); ... kfree_rcu(wb, rcu); wb_shutdown(wb); -> oops use-after-free We solve these issues by synchronizing writeback structure shutdown from cgwb_bdi_unregister() with cgwb_release_workfn() using a new mutex. That way we also no longer need synchronization using WB_shutting_down as the mutex provides it for CONFIG_CGROUP_WRITEBACK case and without CONFIG_CGROUP_WRITEBACK wb_shutdown() can be called only once from bdi_unregister(). Reported-by: syzbot Acked-by: Tejun Heo Signed-off-by: Jan Kara Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

mm: don't do zero_resv_unavail if memmap is not allocated

2018-07-18T05:56:38+00:00

commit d1b47a7c9efcf3c3384b70f6e3c8f1423b44d8c7 upstream. Moving zero_resv_unavail before memmap_init_zone(), caused a regression on x86-32. The cause is that we access struct pages before they are allocated when CONFIG_FLAT_NODE_MEM_MAP is used. free_area_init_nodes() zero_resv_unavail() mm_zero_struct_page(pfn_to_page(pfn)); <- struct page is not alloced free_area_init_node() if CONFIG_FLAT_NODE_MEM_MAP alloc_node_mem_map() memblock_virt_alloc_node_nopanic() <- struct page alloced here On the other hand memblock_virt_alloc_node_nopanic() zeroes all the memory that it returns, so we do not need to do zero_resv_unavail() here. Fixes: e181ae0c5db9 ("mm: zero unavailable pages before memmap init") Signed-off-by: Pavel Tatashin Tested-by: Matt Hart Acked-by: Michal Hocko Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: do not bug_on on incorrect length in __mm_populate()

2018-07-17T09:48:30+00:00

commit bb177a732c4369bb58a1fe1df8f552b6f0f7db5f upstream. syzbot has noticed that a specially crafted library can easily hit VM_BUG_ON in __mm_populate kernel BUG at mm/gup.c:1242! invalid opcode: 0000 [#1] SMP CPU: 2 PID: 9667 Comm: a.out Not tainted 4.18.0-rc3 #644 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017 RIP: 0010:__mm_populate+0x1e2/0x1f0 Code: 55 d0 65 48 33 14 25 28 00 00 00 89 d8 75 21 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 18 f1 ff 0f 0b e8 6e 18 f1 ff <0f> 0b 31 db eb c9 e8 93 06 e0 ff 0f 1f 00 55 48 89 e5 53 48 89 fb Call Trace: vm_brk_flags+0xc3/0x100 vm_brk+0x1f/0x30 load_elf_library+0x281/0x2e0 __ia32_sys_uselib+0x170/0x1e0 do_fast_syscall_32+0xca/0x420 entry_SYSENTER_compat+0x70/0x7f The reason is that the length of the new brk is not page aligned when we try to populate the it. There is no reason to bug on that though. do_brk_flags already aligns the length properly so the mapping is expanded as it should. All we need is to tell mm_populate about it. Besides that there is absolutely no reason to to bug_on in the first place. The worst thing that could happen is that the last page wouldn't get populated and that is far from putting system into an inconsistent state. Fix the issue by moving the length sanitization code from do_brk_flags up to vm_brk_flags. The only other caller of do_brk_flags is brk syscall entry and it makes sure to provide the proper length so t here is no need for sanitation and so we can use do_brk_flags without it. Also remove the bogus BUG_ONs. [osalvador@techadventures.net: fix up vm_brk_flags s@request@len@] Link: http://lkml.kernel.org/r/20180706090217.GI32658@dhcp22.suse.cz Signed-off-by: Michal Hocko Reported-by: syzbot Tested-by: Tetsuo Handa Reviewed-by: Oscar Salvador Cc: Zi Yan Cc: "Aneesh Kumar K.V" Cc: Dan Williams Cc: "Kirill A. Shutemov" Cc: Michael S. Tsirkin Cc: Al Viro Cc: "Huang, Ying" Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman