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<6ae1bde8.f0fe5aea.79aa1.00a0.GAE@google.com> Subject: [syzbot ci] Re: KVM: Fix+harden against bad uaccess using dying VM From: syzbot ci To: jmattson@google.com, jthoughton@google.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, maddy@linux.ibm.com, mason@kernel.org, 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 [v3] KVM: Fix+harden against bad uaccess using dying VM https://lore.kernel.org/all/20261027221209.1560865-1-seanjc@google.com * [PATCH v3 01/15] KVM: Reject user accesses to guest memory if current->mm != kvm->mm * [PATCH v3 02/15] KVM: nVMX: Don't force a full nested VM-Exit when destroying a vCPU * [PATCH v3 03/15] KVM: PPC: Flush/zap all memslots on kvm_arch_flush_shadow_all() * [PATCH v3 04/15] KVM: x86: Unmap VMAs for KVM-internal memslots when the memslot is freed * [PATCH v3 05/15] KVM: Disallow setting memslots when the VM is being destroyed * [PATCH v3 06/15] KVM: Destroy memslots immediately after mmu_notifiers are unregistered * [PATCH v3 07/15] KVM: WARN if KVM attempts to do guest-related uaccess with "wrong" process * [PATCH v3 08/15] KVM: WARN and reject guest-based uaccess if VM is dying * [PATCH v3 09/15] KVM: Pre-check uaccesses in KVM's APIs to read/write guest memory * [PATCH v3 10/15] KVM: VMX: Explicility free vmcs01, not the current VMCS, in vCPU free paths * [PATCH v3 11/15] KVM: nVMX: Don't explicitly VMCLEAR+free() vmcs01's shadow VMCS when freeing vCPU * [PATCH v3 12/15] KVM: nVMX: Cancel the nested VMX Preemption Timer's hrtimer in free_nested() * [PATCH v3 13/15] KVM: VMX: Explicitly remove dying vCPUs from the PI wakeup list * [PATCH v3 14/15] KVM: nVMX: Don't switch to vmcs01 when freeing a vCPU * [PATCH v3 15/15] KVM: nVMX: Don't load+put the vCPU when freeing nested state for a dying vCPU and found the following issue: WARNING in vt_vcpu_pi_remove_from_wakeup_list Full report is available here: https://ci.syzbot.org/series/c648fc23-f4c2-4346-93cd-b717ef38b27c *** WARNING in vt_vcpu_pi_remove_from_wakeup_list tree: kvm-next URL: https://kernel.googlesource.com/pub/scm/virt/kvm/kvm/ base: 7e60162b16f9da0d2fa83da5c1723b6853a0ac1d arch: amd64 compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8 config: https://ci.syzbot.org/builds/e4ed6c4f-9b58-4549-9ac6-525add47e472/config syz repro: https://ci.syzbot.org/findings/320f356a-c5e9-41ff-b8f5-3f0866e300b7/syz_repro ------------[ cut here ]------------ refcount_read(&vcpu->kvm->users_count) WARNING: arch/x86/kvm/vmx/posted_intr.c:154 at vt_vcpu_pi_remove_from_wakeup_list+0x142/0x1f0 arch/x86/kvm/vmx/posted_intr.c:154, CPU#1: syz.2.19/5870 Modules linked in: CPU: 1 UID: 0 PID: 5870 Comm: syz.2.19 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:vt_vcpu_pi_remove_from_wakeup_list+0x142/0x1f0 arch/x86/kvm/vmx/posted_intr.c:154 Code: 48 85 db 74 2d e8 ee 1b 64 00 eb 0c e8 e7 1b 64 00 eb 05 e8 e0 1b 64 00 5b 41 5e 41 5f 5d e9 c5 b5 87 0a cc e8 cf 1b 64 00 90 <0f> 0b 90 e9 2b ff ff ff e8 c1 1b 64 00 e8 ac 60 cf ff eb da 44 89 RSP: 0018:ffffc900037cf8c8 EFLAGS: 00010293 RAX: ffffffff816404a1 RBX: ffff88816ada8000 RCX: ffff888110eb0000 RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000 RBP: 0000000000000003 R08: ffff88810fb01f83 R09: 1ffff11021f603f0 R10: dffffc0000000000 R11: ffffed1021f603f1 R12: dffffc0000000000 R13: 00000000fffffff8 R14: ffff88810fb01f80 R15: dffffc0000000000 FS: 00007f9e487ab6c0(0000) GS:ffff8882a7cbf000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f07a7ed4870 CR3: 000000010eea9000 CR4: 0000000000352ef0 Call Trace: vmx_vcpu_free+0x28/0x400 arch/x86/kvm/vmx/vmx.c:7517 kvm_arch_vcpu_destroy+0x154/0x380 arch/x86/kvm/x86.c:9556 kvm_vm_ioctl_create_vcpu+0x76f/0x9f0 virt/kvm/kvm_main.c:4384 kvm_vm_ioctl+0x442/0xcb0 virt/kvm/kvm_main.c:5294 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9e4799f1eb Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00 RSP: 002b:00007f9e487aaed0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f9e4799f1eb RDX: 0000000000000003 RSI: 000000000000ae41 RDI: 0000000000000085 RBP: 00007f9e47a36b20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000200000c00000 R11: 0000000000000246 R12: 00000000000004ce R13: 0000200000c00000 R14: 0000200000001040 R15: 00007ffeb7342be8 *** 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.