Hello, syzbot found the following issue on: HEAD commit: 521a547ced64 Linux 6.0-rc6 git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=134ea35f080000 kernel config: https://syzkaller.appspot.com/x/.config?x=122d7bd4fc8e0ecb dashboard link: https://syzkaller.appspot.com/bug?extid=6f0c896c5a9449a10ded compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=149bfdd8880000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104808b0880000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6f0c896c5a9449a10ded@xxxxxxxxxxxxxxxxxxxxxxxxx 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: 0 PID: 3606 Comm: syz-executor343 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 <f0> 0f c1 5d 00 bf 01 00 00 00 89 de e8 91 1a 90 ff 83 fb 01 74 35 RSP: 0018:ffffc9000365f748 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: ffffc900037b1000 R15: 00000000ffffffea FS: 0000555556297300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffea CR3: 0000000072461000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> 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 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fd65dc84b69 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc633540b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd65dc84b69 RDX: 0000000020000040 RSI: 000000004048aec9 RDI: 0000000000000004 RBP: 00007fd65dc48d10 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd65dc48da0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> 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 <f0> 0f c1 5d 00 bf 01 00 00 00 89 de e8 91 1a 90 ff 83 fb 01 74 35 RSP: 0018:ffffc9000365f748 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: ffffc900037b1000 R15: 00000000ffffffea FS: 0000555556297300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffea CR3: 0000000072461000 CR4: 00000000003526f0 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 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
