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KMSAN: kernel-infoleak in kvm_vcpu_write_guest_page

Status: fixed on 2019/03/06 07:43
Subsystems: kvm
[Documentation on labels]
Reported-by: syzbot+ded1696f6b50b615b630@syzkaller.appspotmail.com
Fix commit: 3a33d030daaa kvm: x86/vmx: Use kzalloc for cached_vmcs12
First crash: 2018d, last: 1968d
▶ ▼ Duplicate bugs (1)
duplicates (1):
Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
KMSAN: kernel-infoleak in __kvm_write_guest_page kvm 29 1878d 1967d 0/26 closed as dup on 2018/12/06 09:34
▶ ▼ Discussions (4)
Title Replies (including bot) Last reply
[PATCH 4.19 000/103] 4.19.19-stable review 121 (121) 2019/02/01 20:12
[PATCH 4.20 000/117] 4.20.6-stable review 124 (124) 2019/01/31 07:52
[PATCH v2] kvm: x86/vmx: Use kzalloc for cached_vmcs12 2 (2) 2019/01/25 17:52
KMSAN: kernel-infoleak in kvm_vcpu_write_guest_page 15 (16) 2019/01/24 21:46

Sample crash report:
==================================================================
BUG: KMSAN: kernel-infoleak in __copy_to_user include/linux/uaccess.h:121 [inline]
BUG: KMSAN: kernel-infoleak in __kvm_write_guest_page arch/x86/kvm/../../../virt/kvm/kvm_main.c:1849 [inline]
BUG: KMSAN: kernel-infoleak in kvm_vcpu_write_guest_page+0x39a/0x510 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1870
CPU: 0 PID: 7918 Comm: syz-executor542 Not tainted 4.19.0+ #77
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+0x32d/0x480 lib/dump_stack.c:113
 kmsan_report+0x1a2/0x2e0 mm/kmsan/kmsan.c:911
 kmsan_internal_check_memory+0x34c/0x430 mm/kmsan/kmsan.c:991
 kmsan_copy_to_user+0x85/0xe0 mm/kmsan/kmsan_hooks.c:552
 __copy_to_user include/linux/uaccess.h:121 [inline]
 __kvm_write_guest_page arch/x86/kvm/../../../virt/kvm/kvm_main.c:1849 [inline]
 kvm_vcpu_write_guest_page+0x39a/0x510 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1870
 nested_release_vmcs12 arch/x86/kvm/vmx.c:8441 [inline]
 handle_vmptrld+0x2384/0x26b0 arch/x86/kvm/vmx.c:8907
 vmx_handle_exit+0x1e81/0xbac0 arch/x86/kvm/vmx.c:10128
 vcpu_enter_guest arch/x86/kvm/x86.c:7667 [inline]
 vcpu_run arch/x86/kvm/x86.c:7730 [inline]
 kvm_arch_vcpu_ioctl_run+0xac32/0x11d80 arch/x86/kvm/x86.c:7930
 kvm_vcpu_ioctl+0xfb1/0x1f90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
 do_vfs_ioctl+0xf77/0x2d30 fs/ioctl.c:46
 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+0xcf/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x44b6e9
Code: e8 dc e6 ff ff 48 83 c4 18 c3 0f 1f 80 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 0f 83 2b ff fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f096b292ce8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006e3c48 RCX: 000000000044b6e9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00000000006e3c40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00000000006e3c4c
R13: 00007ffd978aeb2f R14: 00007f096b2939c0 R15: 00000000006e3d4c

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:252 [inline]
 kmsan_internal_poison_shadow+0xc8/0x1e0 mm/kmsan/kmsan.c:177
 kmsan_kmalloc+0x98/0x110 mm/kmsan/kmsan_hooks.c:104
 __kmalloc+0x14c/0x4d0 mm/slub.c:3789
 kmalloc include/linux/slab.h:518 [inline]
 enter_vmx_operation+0x980/0x1a90 arch/x86/kvm/vmx.c:8278
 vmx_set_nested_state+0xc3a/0x1530 arch/x86/kvm/vmx.c:14045
 kvm_arch_vcpu_ioctl+0x4fc9/0x73a0 arch/x86/kvm/x86.c:4057
 kvm_vcpu_ioctl+0xca3/0x1f90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2742
 do_vfs_ioctl+0xf77/0x2d30 fs/ioctl.c:46
 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+0xcf/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Bytes 1000-4095 of 4096 are uninitialized
Memory access of size 4096 starts at ffff8801b5157000
==================================================================

Crashes (25):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/11/01 21:00 https://github.com/google/kmsan.git master 88b95ef4c780 1f38e9ae .config console log report syz C ci-upstream-kmsan-gce
2018/10/24 21:20 https://github.com/google/kmsan.git master 4bb25354f0b0 a8292de9 .config console log report syz ci-upstream-kmsan-gce
2018/10/20 13:44 https://github.com/google/kmsan.git master 4bb25354f0b0 ecb386fe .config console log report syz ci-upstream-kmsan-gce
2018/12/05 04:53 https://github.com/google/kmsan.git master 00f99f811392 f162ad97 .config console log report ci-upstream-kmsan-gce
2018/12/04 12:28 https://github.com/google/kmsan.git master 00f99f811392 6ad0ae61 .config console log report ci-upstream-kmsan-gce
2018/12/04 11:19 https://github.com/google/kmsan.git master 00f99f811392 6ad0ae61 .config console log report ci-upstream-kmsan-gce
2018/12/04 02:27 https://github.com/google/kmsan.git master 8f22beb7da7d 03f94a45 .config console log report ci-upstream-kmsan-gce
2018/12/03 15:17 https://github.com/google/kmsan.git master 1d3abf0f2b29 819002b0 .config console log report ci-upstream-kmsan-gce
2018/11/27 02:34 https://github.com/google/kmsan.git master fffec98ae2a6 ac912200 .config console log report ci-upstream-kmsan-gce
2018/11/25 08:54 https://github.com/google/kmsan.git master fffec98ae2a6 3d3ec907 .config console log report ci-upstream-kmsan-gce
2018/11/24 14:06 https://github.com/google/kmsan.git master fffec98ae2a6 ecc7c870 .config console log report ci-upstream-kmsan-gce
2018/11/04 21:50 https://github.com/google/kmsan.git master 88b95ef4c780 8bd6bd63 .config console log report ci-upstream-kmsan-gce
2018/11/03 05:33 https://github.com/google/kmsan.git master 88b95ef4c780 8bd6bd63 .config console log report ci-upstream-kmsan-gce
2018/11/02 10:29 https://github.com/google/kmsan.git master 88b95ef4c780 1f38e9ae .config console log report ci-upstream-kmsan-gce
2018/11/01 19:59 https://github.com/google/kmsan.git master 88b95ef4c780 1f38e9ae .config console log report ci-upstream-kmsan-gce
2018/10/30 09:59 https://github.com/google/kmsan.git master 7e5816e23e06 2f1090da .config console log report ci-upstream-kmsan-gce
2018/10/29 09:38 https://github.com/google/kmsan.git master 4bb25354f0b0 9ca2afa1 .config console log report ci-upstream-kmsan-gce
2018/10/28 22:39 https://github.com/google/kmsan.git master 4bb25354f0b0 9ca2afa1 .config console log report ci-upstream-kmsan-gce
2018/10/26 04:56 https://github.com/google/kmsan.git master 4bb25354f0b0 a8292de9 .config console log report ci-upstream-kmsan-gce
2018/10/25 22:40 https://github.com/google/kmsan.git master 4bb25354f0b0 a8292de9 .config console log report ci-upstream-kmsan-gce
2018/10/24 20:18 https://github.com/google/kmsan.git master 4bb25354f0b0 a8292de9 .config console log report ci-upstream-kmsan-gce
2018/10/20 11:51 https://github.com/google/kmsan.git master 4bb25354f0b0 ecb386fe .config console log report ci-upstream-kmsan-gce
2018/10/18 22:38 https://github.com/google/kmsan.git master 4bb25354f0b0 9aba67b5 .config console log report ci-upstream-kmsan-gce
2018/10/17 05:47 https://github.com/google/kmsan.git master 22ec98c3e38f 1ba7fd7e .config console log report ci-upstream-kmsan-gce
2018/10/16 08:09 https://github.com/google/kmsan.git master 22ec98c3e38f 8cd30605 .config console log report ci-upstream-kmsan-gce
* Struck through repros no longer work on HEAD.