kernel/linux.git, branch v5.13.12

Linux 5.13.12

2021-08-18T07:07:08+00:00

Link: https://lore.kernel.org/r/20210816125444.082226187@linuxfoundation.org Tested-by: Fox Chen Link: https://lore.kernel.org/r/20210816171414.653076979@linuxfoundation.org Tested-by: Shuah Khan Tested-by: Fox Chen Tested-by: Linux Kernel Functional Testing Tested-by: Guenter Roeck

KVM: nSVM: always intercept VMLOAD/VMSAVE when nested (CVE-2021-3656)

2021-08-18T07:07:08+00:00

commit c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc upstream. If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor), then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only possible by making L0 intercept these instructions. Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted, and thus read/write portions of the host physical memory. Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature") Suggested-by: Paolo Bonzini Signed-off-by: Maxim Levitsky Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl (CVE-2021-3653)

2021-08-18T07:07:08+00:00

commit 0f923e07124df069ba68d8bb12324398f4b6b709 upstream. * Invert the mask of bits that we pick from L2 in nested_vmcb02_prepare_control * Invert and explicitly use VIRQ related bits bitmask in svm_clear_vintr This fixes a security issue that allowed a malicious L1 to run L2 with AVIC enabled, which allowed the L2 to exploit the uninitialized and enabled AVIC to read/write the host physical memory at some offsets. Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler") Signed-off-by: Maxim Levitsky Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

kasan, slub: reset tag when printing address

2021-08-18T07:07:08+00:00

commit 340caf178ddc2efb0294afaf54c715f7928c258e upstream. The address still includes the tags when it is printed. With hardware tag-based kasan enabled, we will get a false positive KASAN issue when we access metadata. Reset the tag before we access the metadata. Link: https://lkml.kernel.org/r/20210804090957.12393-3-Kuan-Ying.Lee@mediatek.com Fixes: aa1ef4d7b3f6 ("kasan, mm: reset tags when accessing metadata") Signed-off-by: Kuan-Ying Lee Reviewed-by: Marco Elver Reviewed-by: Andrey Konovalov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Catalin Marinas Cc: Chinwen Chang Cc: Nicholas Tang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ceph: take snap_empty_lock atomically with snaprealm refcount change

2021-08-18T07:07:08+00:00

commit 8434ffe71c874b9c4e184b88d25de98c2bf5fe3f upstream. There is a race in ceph_put_snap_realm. The change to the nref and the spinlock acquisition are not done atomically, so you could decrement nref, and before you take the spinlock, the nref is incremented again. At that point, you end up putting it on the empty list when it shouldn't be there. Eventually __cleanup_empty_realms runs and frees it when it's still in-use. Fix this by protecting the 1->0 transition with atomic_dec_and_lock, and just drop the spinlock if we can get the rwsem. Because these objects can also undergo a 0->1 refcount transition, we must protect that change as well with the spinlock. Increment locklessly unless the value is at 0, in which case we take the spinlock, increment and then take it off the empty list if it did the 0->1 transition. With these changes, I'm removing the dout() messages from these functions, as well as in __put_snap_realm. They've always been racy, and it's better to not print values that may be misleading. Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/46419 Reported-by: Mark Nelson Signed-off-by: Jeff Layton Reviewed-by: Luis Henriques Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap_realm

2021-08-18T07:07:08+00:00

commit df2c0cb7f8e8c83e495260ad86df8c5da947f2a7 upstream. They both say that the snap_rwsem must be held for write, but I don't see any real reason for it, and it's not currently always called that way. The lookup is just walking the rbtree, so holding it for read should be fine there. The "get" is bumping the refcount and (possibly) removing it from the empty list. I see no need to hold the snap_rwsem for write for that. Signed-off-by: Jeff Layton Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: add some lockdep assertions around snaprealm handling

2021-08-18T07:07:07+00:00

commit a6862e6708c15995bc10614b2ef34ca35b4b9078 upstream. Turn some comments into lockdep asserts. Signed-off-by: Jeff Layton Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

KVM: x86/mmu: Protect marking SPs unsync when using TDP MMU with spinlock

2021-08-18T07:07:07+00:00

commit ce25681d59ffc4303321e555a2d71b1946af07da upstream. Add yet another spinlock for the TDP MMU and take it when marking indirect shadow pages unsync. When using the TDP MMU and L1 is running L2(s) with nested TDP, KVM may encounter shadow pages for the TDP entries managed by L1 (controlling L2) when handling a TDP MMU page fault. The unsync logic is not thread safe, e.g. the kvm_mmu_page fields are not atomic, and misbehaves when a shadow page is marked unsync via a TDP MMU page fault, which runs with mmu_lock held for read, not write. Lack of a critical section manifests most visibly as an underflow of unsync_children in clear_unsync_child_bit() due to unsync_children being corrupted when multiple CPUs write it without a critical section and without atomic operations. But underflow is the best case scenario. The worst case scenario is that unsync_children prematurely hits '0' and leads to guest memory corruption due to KVM neglecting to properly sync shadow pages. Use an entirely new spinlock even though piggybacking tdp_mmu_pages_lock would functionally be ok. Usurping the lock could degrade performance when building upper level page tables on different vCPUs, especially since the unsync flow could hold the lock for a comparatively long time depending on the number of indirect shadow pages and the depth of the paging tree. For simplicity, take the lock for all MMUs, even though KVM could fairly easily know that mmu_lock is held for write. If mmu_lock is held for write, there cannot be contention for the inner spinlock, and marking shadow pages unsync across multiple vCPUs will be slow enough that bouncing the kvm_arch cacheline should be in the noise. Note, even though L2 could theoretically be given access to its own EPT entries, a nested MMU must hold mmu_lock for write and thus cannot race against a TDP MMU page fault. I.e. the additional spinlock only _needs_ to be taken by the TDP MMU, as opposed to being taken by any MMU for a VM that is running with the TDP MMU enabled. Holding mmu_lock for read also prevents the indirect shadow page from being freed. But as above, keep it simple and always take the lock. Alternative #1, the TDP MMU could simply pass "false" for can_unsync and effectively disable unsync behavior for nested TDP. Write protecting leaf shadow pages is unlikely to noticeably impact traditional L1 VMMs, as such VMMs typically don't modify TDP entries, but the same may not hold true for non-standard use cases and/or VMMs that are migrating physical pages (from L1's perspective). Alternative #2, the unsync logic could be made thread safe. In theory, simply converting all relevant kvm_mmu_page fields to atomics and using atomic bitops for the bitmap would suffice. However, (a) an in-depth audit would be required, (b) the code churn would be substantial, and (c) legacy shadow paging would incur additional atomic operations in performance sensitive paths for no benefit (to legacy shadow paging). Fixes: a2855afc7ee8 ("KVM: x86/mmu: Allow parallel page faults for the TDP MMU") Cc: stable@vger.kernel.org Cc: Ben Gardon Signed-off-by: Sean Christopherson Message-Id: <20210812181815.3378104-1-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: x86/mmu: Don't leak non-leaf SPTEs when zapping all SPTEs

2021-08-18T07:07:07+00:00

commit 524a1e4e381fc5e7781008d5bd420fd1357c0113 upstream. Pass "all ones" as the end GFN to signal "zap all" for the TDP MMU and really zap all SPTEs in this case. As is, zap_gfn_range() skips non-leaf SPTEs whose range exceeds the range to be zapped. If shadow_phys_bits is not aligned to the range size of top-level SPTEs, e.g. 512gb with 4-level paging, the "zap all" flows will skip top-level SPTEs whose range extends beyond shadow_phys_bits and leak their SPs when the VM is destroyed. Use the current upper bound (based on host.MAXPHYADDR) to detect that the caller wants to zap all SPTEs, e.g. instead of using the max theoretical gfn, 1 << (52 - 12). The more precise upper bound allows the TDP iterator to terminate its walk earlier when running on hosts with MAXPHYADDR < 52. Add a WARN on kmv->arch.tdp_mmu_pages when the TDP MMU is destroyed to help future debuggers should KVM decide to leak SPTEs again. The bug is most easily reproduced by running (and unloading!) KVM in a VM whose host.MAXPHYADDR < 39, as the SPTE for gfn=0 will be skipped. ============================================================================= BUG kvm_mmu_page_header (Not tainted): Objects remaining in kvm_mmu_page_header on __kmem_cache_shutdown() ----------------------------------------------------------------------------- Slab 0x000000004d8f7af1 objects=22 used=2 fp=0x00000000624d29ac flags=0x4000000000000200(slab|zone=1) CPU: 0 PID: 1582 Comm: rmmod Not tainted 5.14.0-rc2+ #420 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack_lvl+0x45/0x59 slab_err+0x95/0xc9 __kmem_cache_shutdown.cold+0x3c/0x158 kmem_cache_destroy+0x3d/0xf0 kvm_mmu_module_exit+0xa/0x30 [kvm] kvm_arch_exit+0x5d/0x90 [kvm] kvm_exit+0x78/0x90 [kvm] vmx_exit+0x1a/0x50 [kvm_intel] __x64_sys_delete_module+0x13f/0x220 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixes: faaf05b00aec ("kvm: x86/mmu: Support zapping SPTEs in the TDP MMU") Cc: stable@vger.kernel.org Cc: Ben Gardon Signed-off-by: Sean Christopherson Message-Id: <20210812181414.3376143-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: nVMX: Use vmx_need_pf_intercept() when deciding if L0 wants a #PF

2021-08-18T07:07:07+00:00

commit 18712c13709d2de9516c5d3414f707c4f0a9c190 upstream. Use vmx_need_pf_intercept() when determining if L0 wants to handle a #PF in L2 or if the VM-Exit should be forwarded to L1. The current logic fails to account for the case where #PF is intercepted to handle guest.MAXPHYADDR < host.MAXPHYADDR and ends up reflecting all #PFs into L1. At best, L1 will complain and inject the #PF back into L2. At worst, L1 will eat the unexpected fault and cause L2 to hang on infinite page faults. Note, while the bug was technically introduced by the commit that added support for the MAXPHYADDR madness, the shame is all on commit a0c134347baf ("KVM: VMX: introduce vmx_need_pf_intercept"). Fixes: 1dbf5d68af6f ("KVM: VMX: Add guest physical address check in EPT violation and misconfig") Cc: stable@vger.kernel.org Cc: Peter Shier Cc: Oliver Upton Cc: Jim Mattson Signed-off-by: Sean Christopherson Message-Id: <20210812045615.3167686-1-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman