L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details. BUG: unable to handle page fault for address: ffffffffffffffea #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD bc8f067 P4D bc8f067 PUD bc91067 PMD 0 Oops: 0002 [#1] PREEMPT SMP KASAN CPU: 1 PID: 3599 Comm: syz-executor287 Not tainted 6.0.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 RIP: 0010:arch_atomic_fetch_sub arch/x86/include/asm/atomic.h:190 [inline] RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline] RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:272 [inline] RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:315 [inline] RIP: 0010:refcount_dec_and_test include/linux/refcount.h:333 [inline] RIP: 0010:kref_put include/linux/kref.h:64 [inline] RIP: 0010:eventfd_ctx_put+0x1e/0x110 fs/eventfd.c:112 Code: ff ff e8 65 7e dc ff e9 b5 fb ff ff 41 54 55 48 89 fd 53 bb ff ff ff ff e8 ef 1d 90 ff be 04 00 00 00 48 89 ef e8 72 80 dc ff 0f c1 5d 00 bf 01 00 00 00 89 de e8 91 1a 90 ff 83 fb 01 74 35 RSP: 0018:ffffc900037ef5e8 EFLAGS: 00010246 RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff81ebeb3e RDX: fffffbfffffffffe RSI: 0000000000000004 RDI: ffffffffffffffea RBP: ffffffffffffffea R08: 0000000000000001 R09: ffffffffffffffed R10: fffffbfffffffffd R11: 0000000000000000 R12: 0000000000000003 R13: ffffffffffffffea R14: ffffc90003821000 R15: 00000000ffffffea FS: 0000000000000000(0000) GS:ffff8880b9b00000(0063) knlGS:00000000570452c0 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: ffffffffffffffea CR3: 000000001bf17000 CR4: 00000000003526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kvm_xen_eventfd_assign arch/x86/kvm/xen.c:1721 [inline] kvm_xen_setattr_evtchn arch/x86/kvm/xen.c:1780 [inline] kvm_xen_hvm_set_attr+0x563/0x1610 arch/x86/kvm/xen.c:486 kvm_arch_vm_ioctl+0xe39/0x18b0 arch/x86/kvm/x86.c:6790 kvm_vm_ioctl+0x15df/0x2380 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4811 kvm_vm_compat_ioctl+0x288/0x350 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4880 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:968 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 RIP: 0023:0xf7ed1549 Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000ffaa98ac EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000004048aec9 RDX: 0000000020000040 RSI: 00000000ffaa9900 RDI: 00000000f7f74000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Modules linked in: CR2: ffffffffffffffea ---[ end trace 0000000000000000 ]--- RIP: 0010:arch_atomic_fetch_sub arch/x86/include/asm/atomic.h:190 [inline] RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline] RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:272 [inline] RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:315 [inline] RIP: 0010:refcount_dec_and_test include/linux/refcount.h:333 [inline] RIP: 0010:kref_put include/linux/kref.h:64 [inline] RIP: 0010:eventfd_ctx_put+0x1e/0x110 fs/eventfd.c:112 Code: ff ff e8 65 7e dc ff e9 b5 fb ff ff 41 54 55 48 89 fd 53 bb ff ff ff ff e8 ef 1d 90 ff be 04 00 00 00 48 89 ef e8 72 80 dc ff 0f c1 5d 00 bf 01 00 00 00 89 de e8 91 1a 90 ff 83 fb 01 74 35 RSP: 0018:ffffc900037ef5e8 EFLAGS: 00010246 RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff81ebeb3e RDX: fffffbfffffffffe RSI: 0000000000000004 RDI: ffffffffffffffea RBP: ffffffffffffffea R08: 0000000000000001 R09: ffffffffffffffed R10: fffffbfffffffffd R11: 0000000000000000 R12: 0000000000000003 R13: ffffffffffffffea R14: ffffc90003821000 R15: 00000000ffffffea FS: 0000000000000000(0000) GS:ffff8880b9b00000(0063) knlGS:00000000570452c0 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: ffffffffffffffea CR3: 000000001bf17000 CR4: 00000000003526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: e8 65 7e dc ff callq 0xffdc7e6a 5: e9 b5 fb ff ff jmpq 0xfffffbbf a: 41 54 push %r12 c: 55 push %rbp d: 48 89 fd mov %rdi,%rbp 10: 53 push %rbx 11: bb ff ff ff ff mov $0xffffffff,%ebx 16: e8 ef 1d 90 ff callq 0xff901e0a 1b: be 04 00 00 00 mov $0x4,%esi 20: 48 89 ef mov %rbp,%rdi 23: e8 72 80 dc ff callq 0xffdc809a * 28: f0 0f c1 5d 00 lock xadd %ebx,0x0(%rbp) <-- trapping instruction 2d: bf 01 00 00 00 mov $0x1,%edi 32: 89 de mov %ebx,%esi 34: e8 91 1a 90 ff callq 0xff901aca 39: 83 fb 01 cmp $0x1,%ebx 3c: 74 35 je 0x73