kernel/linux.git/arch/x86, branch v5.15.211

KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path

2026-07-04T11:39:40+00:00

commit 78ee2d50185a037b3d2452a97f3dad69c3f7f389 upstream. In sev_dbg_crypt(), the per-iteration transfer length is bounded by the source page offset (PAGE_SIZE - s_off) but not by the destination page offset (PAGE_SIZE - d_off). When d_off > s_off, the encrypt path (__sev_dbg_encrypt_user) performs a read-modify-write using a single-page intermediate buffer (dst_tpage): 1. __sev_dbg_decrypt() expands the size to round_up(len + (d_off & 15), 16) before issuing the PSP command. If len + (d_off & 15) > PAGE_SIZE, the PSP writes beyond the end of the 4096-byte dst_tpage allocation. 2. The subsequent memcpy()/copy_from_user() into page_address(dst_tpage) + (d_off & 15) of 'len' bytes overflows by up to 15 bytes under the same condition. Trigger example: s_off = 0, d_off = 1, debug.len = PAGE_SIZE - the PSP is instructed to write round_up(4097, 16) = 4112 bytes to a 4096-byte buffer. Fix by also bounding len by (PAGE_SIZE - d_off), the same check that sev_send_update_data() already performs for its single-page guest region. ================================================================== BUG: KASAN: slab-use-after-free in sev_dbg_crypt+0x993/0xd10 [kvm_amd] Write of size 4095 at addr ff110062293bb009 by task sev_dbg_test/228214 CPU: 96 UID: 0 PID: 228214 Comm: sev_dbg_test Tainted: G U W 7.0.0-smp--5ce9b0c48211-dbg #156 PREEMPTLAZY Tainted: [U]=USER, [W]=WARN Hardware name: Google Astoria/astoria, BIOS 0.20250817.1-0 08/25/2025 Call Trace: dump_stack_lvl+0x54/0x70 print_report+0xbc/0x260 kasan_report+0xa2/0xd0 kasan_check_range+0x25f/0x2c0 __asan_memcpy+0x40/0x70 sev_dbg_crypt+0x993/0xd10 [kvm_amd] sev_mem_enc_ioctl+0x33c/0x450 [kvm_amd] kvm_vm_ioctl+0x65d/0x6d0 [kvm] __se_sys_ioctl+0xb2/0x100 do_syscall_64+0xe8/0x870 entry_SYSCALL_64_after_hwframe+0x4b/0x53 The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x7fe72b6a0 pfn:0x62293bb memcg:ff11000112827d82 flags: 0x1400000000000000(node=1|zone=1) raw: 1400000000000000 0000000000000000 dead000000000122 0000000000000000 raw: 00000007fe72b6a0 0000000000000000 00000001ffffffff ff11000112827d82 page dumped because: kasan: bad access detected Memory state around the buggy address: ff110062293bbf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff110062293bbf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ff110062293bc000: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ff110062293bc080: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ff110062293bc100: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint Fixes: 24f41fb23a39 ("KVM: SVM: Add support for SEV DEBUG_DECRYPT command") Fixes: 7d1594f5d94b ("KVM: SVM: Add support for SEV DEBUG_ENCRYPT command") Cc: stable@vger.kernel.org Signed-off-by: Ashutosh Desai [sean: add sample KASAN splat, Fixes, and stable@] Link: https://patch.msgid.link/20260501203537.2120074-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman

KVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level

2026-07-04T11:39:37+00:00

commit ef057cbf825e03b63f6edf5980f96abf3c53089d upstream. When recovering hugepages in the shadow MMU, verify that the base gfn of the shadow page is actually contained within the target memslot, *before* querying the max mapping level given the shadow page's gfn. Failure to pre-check the validity of the gfn can lead to an out-of-bounds access to the slot's lpage_info (which typically manifests as a host #PF because the lpage_info is vmalloc'd) if the guest creates a hugepage mapping (in its PTEs) that extends "below" the bounds of a memslot. When faulting in memory for a guest, and the size of the guest mapping is greater than KVM's (current) max mapping, then KVM will create a "direct" shadow page (direct in that there are no gPTEs to shadow, and so the target gfn is a direct calculation given the base gfn of the shadow page). The hugepage recovery flow looks for such direct shadow pages, as forcing 4KiB mappings when dirty logging generates the guest > host mapping size case. When the 4KiB restriction is lifted, then KVM can replace the shadow page with a hugepage. But if KVM originally used a smaller mapping than the guest because the range of memory covered by the guest hugepage exceeds the bounds of a memslot, then KVM will link a direct shadow page with a gfn that is outside the bounds of the memslot being used to fault in memory. The rmap entry added for the leaf mapping is correct and within bounds, but the gfn of the leaf SPTE's parent shadow page will be out of bounds. BUG: unable to handle page fault for address: ffffc90000806ffc #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 100000067 P4D 100000067 PUD 1002a7067 PMD 10612f067 PTE 0 Oops: Oops: 0000 [#1] SMP CPU: 13 UID: 1000 PID: 757 Comm: mmu_stress_test Not tainted 7.1.0-rc1-48ce1e26eace-x86_pir_to_irr_comments-vm #341 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:kvm_mmu_max_mapping_level+0x79/0x2b0 [kvm] Call Trace: kvm_mmu_recover_huge_pages+0x21b/0x320 [kvm] kvm_set_memslot+0x1ee/0x590 [kvm] kvm_set_memory_region.part.0+0x3a1/0x4d0 [kvm] kvm_vm_ioctl+0x9bf/0x15d0 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb7/0xbb0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f21c0f1a9bf Don't bother pre-checking the bounds of the potential hugepage, i.e. don't check that e.g. sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1) is also within the memslot, as the checks performed by kvm_mmu_max_mapping_level() are a superset of the basic bounds checks. I.e. pre-checking the full range would be a dubious micro-optimization. Fixes: 9eba50f8d7fc ("KVM: x86/mmu: Consult max mapping level when zapping collapsible SPTEs") Cc: stable@vger.kernel.org Cc: David Matlack Cc: James Houghton Cc: Alexander Bulekov Cc: Fred Griffoul Cc: Alexander Graf Cc: David Woodhouse Cc: Filippo Sironi Cc: Ivan Orlov Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin

x86/CPU/AMD: Move the Zen3 BTC_NO detection to the Zen3 init function

2026-06-19T11:33:50+00:00

commit affc66cb96f865b3763a8e18add52e133d864f04 upstream. No functional changes. Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Nikolay Borisov Link: http://lore.kernel.org/r/20231120104152.13740-4-bp@alien8.de Stable-dep-of: 7c81ad8e8bc2 ("x86/CPU/AMD: Rename init_amd_zn() to init_amd_zen_common()") [bwh: Adjusted to apply after backports of the above commit which actually depended on this] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

use less confusing names for iov_iter direction initializers

2026-06-19T11:33:46+00:00

[ Upstream commit de4eda9de2d957ef2d6a8365a01e26a435e958cb ] READ/WRITE proved to be actively confusing - the meanings are "data destination, as used with read(2)" and "data source, as used with write(2)", but people keep interpreting those as "we read data from it" and "we write data to it", i.e. exactly the wrong way. Call them ITER_DEST and ITER_SOURCE - at least that is harder to misinterpret... Signed-off-by: Al Viro Stable-dep-of: a4f0b001782b ("vsock/virtio: reset connection on receiving queue overflow") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: x86: Acquire SRCU in KVM_GET_MP_STATE to protect guest memory accesses

2026-06-01T15:35:46+00:00

commit ef01cac401f18647d62720cf773d7bb0541827da upstream. Acquire a lock on kvm->srcu when userspace is getting MP state to handle a rather extreme edge case where "accepting" APIC events, i.e. processing pending INIT or SIPI, can trigger accesses to guest memory. If the vCPU is in L2 with INIT *and* a TRIPLE_FAULT request pending, then getting MP state will trigger a nested VM-Exit by way of ->check_nested_events(), and emuating the nested VM-Exit can access guest memory. The splat was originally hit by syzkaller on a Google-internal kernel, and reproduced on an upstream kernel by hacking the triple_fault_event_test selftest to stuff a pending INIT, store an MSR on VM-Exit (to generate a memory access on VMX), and do vcpu_mp_state_get() to trigger the scenario. ============================= WARNING: suspicious RCU usage 6.14.0-rc3-b112d356288b-vmx/pi_lockdep_false_pos-lock #3 Not tainted ----------------------------- include/linux/kvm_host.h:1058 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by triple_fault_ev/1256: #0: ffff88810df5a330 (&vcpu->mutex){+.+.}-{4:4}, at: kvm_vcpu_ioctl+0x8b/0x9a0 [kvm] stack backtrace: CPU: 11 UID: 1000 PID: 1256 Comm: triple_fault_ev Not tainted 6.14.0-rc3-b112d356288b-vmx #3 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack_lvl+0x7f/0x90 lockdep_rcu_suspicious+0x144/0x190 kvm_vcpu_gfn_to_memslot+0x156/0x180 [kvm] kvm_vcpu_read_guest+0x3e/0x90 [kvm] read_and_check_msr_entry+0x2e/0x180 [kvm_intel] __nested_vmx_vmexit+0x550/0xde0 [kvm_intel] kvm_check_nested_events+0x1b/0x30 [kvm] kvm_apic_accept_events+0x33/0x100 [kvm] kvm_arch_vcpu_ioctl_get_mpstate+0x30/0x1d0 [kvm] kvm_vcpu_ioctl+0x33e/0x9a0 [kvm] __x64_sys_ioctl+0x8b/0xb0 do_syscall_64+0x6c/0x170 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-ID: <20250401150504.829812-1-seanjc@google.com> Signed-off-by: Paolo Bonzini [ Based on kernel 5.15 available functions, using srcu_read_lock/srcu_read_unlock instead of kvm_vcpu_srcu_read_lock/kvm_vcpu_srcu_read_unlock ] Signed-off-by: Rajani Kantha <681739313@139.com> Signed-off-by: Sasha Levin

Revert "x86/vdso: Fix output operand size of RDPID"

2026-06-01T15:35:45+00:00

This reverts commit 64f14b1ab6f39a704b62bf9b3fa28803cf2b3ebe. Signed-off-by: Sasha Levin

KVM: x86: Fix Xen hypercall tracepoint argument assignment

2026-06-01T15:35:44+00:00

commit 2b72f1674e427c56e3772c5ccf785fdda2138820 upstream. TRACE_EVENT(kvm_xen_hypercall) stores a5 in __entry->a4 instead of __entry->a5. That overwrites the recorded a4 argument and leaves a5 unset in the trace entry. Fix the typo so both arguments are captured correctly. Signed-off-by: Qiang Ma Link: https://patch.msgid.link/20260512015313.1685784-1-maqianga@uniontech.com/ Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

KVM: nSVM: Add missing consistency check for nCR3 validity

2026-06-01T15:35:16+00:00

commit b71138fcc362c67ebe66747bb22cb4e6b4d6a651 upstream. From the APM Volume #2, 15.25.4 (24593—Rev. 3.42—March 2024): When VMRUN is executed with nested paging enabled (NP_ENABLE = 1), the following conditions are considered illegal state combinations, in addition to those mentioned in “Canonicalization and Consistency Checks”: • Any MBZ bit of nCR3 is set. • Any G_PAT.PA field has an unsupported type encoding or any reserved field in G_PAT has a nonzero value. Add the consistency check for nCR3 being a legal GPA with no MBZ bits set. Note, the G_PAT.PA check is being handled separately[*]. Link: https://lore.kernel.org/kvm/20260205214326.1029278-3-jmattson@google.com [*] Fixes: 4b16184c1cca ("KVM: SVM: Initialize Nested Nested MMU context on VMRUN") Cc: stable@vger.kernel.org Signed-off-by: Yosry Ahmed Link: https://patch.msgid.link/20260303003421.2185681-16-yosry@kernel.org [sean: capture everything in CC(), massage changelog formatting] Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman

KVM: nSVM: Clear GIF on nested #VMEXIT(INVALID)

2026-06-01T15:35:16+00:00

commit f85a6ce06e4a0d49652f57967a649ab09e06287c upstream. According to the APM, GIF is set to 0 on any #VMEXIT, including an #VMEXIT(INVALID) due to failed consistency checks. Clear GIF on consistency check failures. Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler") Cc: stable@vger.kernel.org Signed-off-by: Yosry Ahmed Link: https://patch.msgid.link/20260303003421.2185681-11-yosry@kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman

KVM: nSVM: Always inject a #GP if mapping VMCB12 fails on nested VMRUN

2026-06-01T15:35:16+00:00

commit 01ddcdc55e097ca38c28ae656711b8e6d1df71f8 upstream. nested_svm_vmrun() currently only injects a #GP if kvm_vcpu_map() fails with -EINVAL. But it could also fail with -EFAULT if creating a host mapping failed. Inject a #GP in all cases, no reason to treat failure modes differently. Fixes: 8c5fbf1a7231 ("KVM/nSVM: Use the new mapping API for mapping guest memory") CC: stable@vger.kernel.org Co-developed-by: Sean Christopherson Signed-off-by: Yosry Ahmed Link: https://patch.msgid.link/20260303003421.2185681-6-yosry@kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman