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2002:a05:6808:bd4:b0:4d6:9133:cfee with SMTP id 5614622812f47-4f30caa6c35mr5991865b6e.51.1790973023528; Fri, 02 Oct 2026 13:30:23 -0700 (PDT) Date: Fri, 02 Oct 2026 13:30:23 -0700 In-Reply-To: <20261001202234.3794060-1-seanjc@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ac0145f.34119e79.2f92f3.0003.GAE@google.com> Subject: [syzbot ci] Re: KVM: Fix+harden against bad uaccess using dying VM From: syzbot ci To: jmattson@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, maddy@linux.ibm.com, npiggin@gmail.com, pbonzini@redhat.com, seanjc@google.com Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v2] KVM: Fix+harden against bad uaccess using dying VM https://lore.kernel.org/all/20261001202234.3794060-1-seanjc@google.com * [PATCH v2 01/10] KVM: Reject user accesses to guest memory if current->mm != kvm->mm * [PATCH v2 02/10] KVM: PPC: Flush/zap all memslots on kvm_arch_flush_shadow_all() * [PATCH v2 03/10] KVM: x86: Unmap VMAs for KVM-internal memslots when the memslot is freed * [PATCH v2 04/10] KVM: Disallow setting memslots when the VM is being destroyed * [PATCH v2 05/10] KVM: Destroy memslots immediately after mmu_notifiers are unregistered * [PATCH v2 06/10] KVM: WARN if KVM attempts to do guest-related uaccess with "wrong" process * [PATCH v2 07/10] KVM: WARN and reject guest-based uaccess if VM is dying * [PATCH v2 08/10] KVM: nVMX: Don't flush shadow VMCS12 to guest memory during vCPU teardown * [PATCH v2 09/10] KVM: nVMX: Don't try to load eVMCS12 page when the VM is dying * [PATCH v2 10/10] KVM: Pre-check uaccesses in KVM's APIs to read/write guest memory and found the following issue: WARNING in __kvm_read_guest_page Full report is available here: https://ci.syzbot.org/series/5f8da53a-c584-4176-abcb-7a29eb02e4c4 *** WARNING in __kvm_read_guest_page tree: kvm-next URL: https://kernel.googlesource.com/pub/scm/virt/kvm/kvm/ base: d4b7fb647204f0c81dfeae2d1a708e4d858e0c94 arch: amd64 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 config: https://ci.syzbot.org/builds/4d4c10d0-f56c-448f-8782-ad4dab8f46d0/config syz repro: https://ci.syzbot.org/findings/dc5f6c42-c3ab-41b0-9384-1a15798e4820/syz_repro ------------[ cut here ]------------ !__kvm_can_do_uaccess(kvm) WARNING: ./include/linux/kvm_host.h:1360 at kvm_can_do_uaccess include/linux/kvm_host.h:1360 [inline], CPU#1: syz.1.18/5858 WARNING: ./include/linux/kvm_host.h:1360 at kvm_is_guest_access_ok virt/kvm/kvm_main.c:3216 [inline], CPU#1: syz.1.18/5858 WARNING: ./include/linux/kvm_host.h:1360 at __kvm_read_guest_page+0x38e/0x440 virt/kvm/kvm_main.c:3226, CPU#1: syz.1.18/5858 Modules linked in: CPU: 1 UID: 0 PID: 5858 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:kvm_can_do_uaccess include/linux/kvm_host.h:1360 [inline] RIP: 0010:kvm_is_guest_access_ok virt/kvm/kvm_main.c:3216 [inline] RIP: 0010:__kvm_read_guest_page+0x38e/0x440 virt/kvm/kvm_main.c:3226 Code: f2 ff ff ff 0f 44 d8 31 ff e8 5e a4 89 00 89 d8 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d e9 09 ac a8 0a cc e8 83 9e 89 00 90 <0f> 0b 90 bb f2 ff ff ff eb da e8 73 9e 89 00 90 0f 0b 90 bb f2 ff RSP: 0018:ffffc90003157778 EFLAGS: 00010293 RAX: ffffffff813e2d22 RBX: 0000000000000000 RCX: ffff888174382580 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 1ffff1102217d82a R08: ffff888110bee183 R09: 1ffff1102217dc30 R10: dffffc0000000000 R11: ffffed102217dc31 R12: ffff888110bee180 R13: ffff888174382b40 R14: 1ffff1102217dc30 R15: 0000000000000000 FS: 000055557c0db500(0000) GS:ffff8882a8cda000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f458dfeb840 CR3: 000000016c9d0000 CR4: 0000000000352ef0 Call Trace: kvm_vcpu_read_guest+0x64/0x140 virt/kvm/kvm_main.c:3284 nested_vmx_load_msr+0x133/0x4d0 arch/x86/kvm/vmx/nested.c:1107 load_vmcs12_host_state+0x10ca/0x1e20 arch/x86/kvm/vmx/nested.c:4930 __nested_vmx_vmexit+0x1800/0x2d10 arch/x86/kvm/vmx/nested.c:5206 nested_vmx_vmexit arch/x86/kvm/vmx/nested.h:46 [inline] vmx_leave_nested arch/x86/kvm/vmx/nested.c:6891 [inline] nested_vmx_free_vcpu+0x8e/0xd0 arch/x86/kvm/vmx/nested.c:389 vmx_vcpu_free+0x109/0x3e0 arch/x86/kvm/vmx/vmx.c:7653 kvm_arch_vcpu_destroy+0x154/0x380 arch/x86/kvm/x86.c:9463 kvm_vcpu_destroy virt/kvm/kvm_main.c:469 [inline] kvm_destroy_vcpus+0x123/0x380 virt/kvm/kvm_main.c:489 kvm_arch_destroy_vm+0x55/0x120 arch/x86/kvm/x86.c:10014 kvm_destroy_vm virt/kvm/kvm_main.c:1326 [inline] kvm_put_kvm+0x93a/0xc80 virt/kvm/kvm_main.c:1359 kvm_vm_release+0x43/0x50 virt/kvm/kvm_main.c:1382 __fput+0x418/0xa50 fs/file_table.c:512 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7fec79e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff0d2850c8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f7feca27da0 RCX: 00007f7fec79e159 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f7feca27da0 R08: 00007f7feca26038 R09: 0000000000000000 R10: 000000000003fdb8 R11: 0000000000000246 R12: 000000000000ec04 R13: 00007f7feca25fac R14: 000000000000e938 R15: 00007fff0d2851d0 *** If these findings have caused you to resend the series or submit a separate fix, please add the following tag to your commit message: Tested-by: syzbot@syzkaller.appspotmail.com --- This report is generated by a bot. It may contain errors. syzbot ci engineers can be reached at syzkaller@googlegroups.com. To test a fix for this bug, please reply with `#syz test` (on a separate line) and attach the patch to the email. Notes: - The patch will be applied on top of the tested series (as an incremental fix). - To test a new version of the whole series, please send it directly to syzbot@lists.linux.dev. - Arguments like custom git repos and branches are not supported.