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KMSAN: uninit-value in vmx_handle_external_intr

Status: closed as invalid on 2018/10/10 13:24
Subsystems: kvm
[Documentation on labels]
First crash: 1998d, last: 1997d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in vmx_handle_external_intr (2) kvm 1 1995d 1995d 0/26 auto-closed as invalid on 2019/04/09 13:13

Sample crash report:
L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.
audit: type=1326 audit(1539136792.351:40): auid=4294967295 uid=0 gid=0 ses=4294967295 subj==unconfined pid=7997 comm="syz-executor5" exe="/root/syz-executor5" sig=31 arch=c000003e syscall=228 compat=0 ip=0x45a3da code=0xffff0000
==================================================================
BUG: KMSAN: uninit-value in gate_offset arch/x86/include/asm/desc_defs.h:93 [inline]
BUG: KMSAN: uninit-value in vmx_handle_external_intr+0x244/0x280 arch/x86/kvm/vmx.c:10417
CPU: 0 PID: 8027 Comm: syz-executor0 Not tainted 4.19.0-rc4+ #65
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x306/0x460 lib/dump_stack.c:113
 kmsan_report+0x1a2/0x2e0 mm/kmsan/kmsan.c:917
 __msan_warning+0x7c/0xe0 mm/kmsan/kmsan_instr.c:500
 gate_offset arch/x86/include/asm/desc_defs.h:93 [inline]
 vmx_handle_external_intr+0x244/0x280 arch/x86/kvm/vmx.c:10417
 vcpu_enter_guest arch/x86/kvm/x86.c:7621 [inline]
 vcpu_run arch/x86/kvm/x86.c:7711 [inline]
 kvm_arch_vcpu_ioctl_run+0x9d7a/0x10a20 arch/x86/kvm/x86.c:7888
 kvm_vcpu_ioctl+0x11a7/0x20b0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xcf3/0x2810 fs/ioctl.c:687
 ksys_ioctl fs/ioctl.c:702 [inline]
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:707
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:707
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457579
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f668635cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f668635d6d4
R13: 00000000004c003b R14: 00000000004d0108 R15: 00000000ffffffff

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:255 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:270 [inline]
 kmsan_internal_chain_origin+0x136/0x240 mm/kmsan/kmsan.c:572
 __msan_chain_origin+0x75/0xd0 mm/kmsan/kmsan_instr.c:337
 vmx_set_constant_host_state+0xf1a/0x1830 arch/x86/kvm/vmx.c:6325
 vmx_vcpu_setup arch/x86/kvm/vmx.c:6618 [inline]
 vmx_create_vcpu+0x3e6f/0x7870 arch/x86/kvm/vmx.c:11010
 kvm_arch_vcpu_create+0x25d/0x2f0 arch/x86/kvm/x86.c:8452
 kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:2476 [inline]
 kvm_vm_ioctl+0x13fd/0x33d0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2977
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xcf3/0x2810 fs/ioctl.c:687
 ksys_ioctl fs/ioctl.c:702 [inline]
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:707
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:707
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Local variable description: ----dt@vmx_set_constant_host_state
Variable was created at:
 vmx_set_constant_host_state+0x2b0/0x1830 arch/x86/kvm/vmx.c:6284
 vmx_vcpu_setup arch/x86/kvm/vmx.c:6618 [inline]
 vmx_create_vcpu+0x3e6f/0x7870 arch/x86/kvm/vmx.c:11010
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/10/10 02:00 https://github.com/google/kmsan.git master c2d21df4c5af 8b311eaf .config console log report ci-upstream-kmsan-gce
2018/10/09 14:33 https://github.com/google/kmsan.git master c2d21df4c5af 8b311eaf .config console log report ci-upstream-kmsan-gce
2018/10/09 10:03 https://github.com/google/kmsan.git master c2d21df4c5af 8b311eaf .config console log report ci-upstream-kmsan-gce
* Struck through repros no longer work on HEAD.