syzbot


KASAN: slab-out-of-bounds Read in gfn_to_memslot

Status: closed as dup on 2020/04/14 03:20
Subsystems: kvm
[Documentation on labels]
Reported-by: syzbot+2e0179e5185bcd5b9440@syzkaller.appspotmail.com
First crash: 1420d, last: 1412d
Cause bisection: introduced by (bisect log) :
commit 36947254e5f981aeeedab1c7dfa35fc34d330e80
Author: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Tue Feb 18 21:07:32 2020 +0000

  KVM: Dynamically size memslot array based on number of used slots

Crash: KASAN: slab-out-of-bounds Read in gfn_to_hva (log)
Repro: C syz .config
  
Duplicate of
Title Repro Cause bisect Fix bisect Count Last Reported
KASAN: slab-out-of-bounds Read in __kvm_gfn_to_hva_cache_init kvm C done 1537 1380d 1425d
Discussions (1)
Title Replies (including bot) Last reply
KASAN: slab-out-of-bounds Read in gfn_to_memslot 1 (3) 2020/04/14 03:20

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in search_memslots include/linux/kvm_host.h:1051 [inline]
BUG: KASAN: slab-out-of-bounds in __gfn_to_memslot include/linux/kvm_host.h:1063 [inline]
BUG: KASAN: slab-out-of-bounds in gfn_to_memslot+0x275/0x470 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1597
Read of size 8 at addr ffff888097b31468 by task syz-executor165/9960

CPU: 0 PID: 9960 Comm: syz-executor165 Not tainted 5.6.0-syzkaller #0
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+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:382
 __kasan_report+0x103/0x1a0 mm/kasan/report.c:511
 kasan_report+0x4d/0x80 mm/kasan/common.c:625

Allocated by task 9966:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0x81/0x100 mm/util.c:574
 kvmalloc include/linux/mm.h:757 [inline]
 kvzalloc include/linux/mm.h:765 [inline]
 kvm_dup_memslots arch/x86/kvm/../../../virt/kvm/kvm_main.c:1101 [inline]
 kvm_set_memslot+0x124/0x15b0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1118
 __kvm_set_memory_region+0x1388/0x16c0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1300
 kvm_set_memory_region arch/x86/kvm/../../../virt/kvm/kvm_main.c:1321 [inline]
 kvm_vm_ioctl_set_memory_region arch/x86/kvm/../../../virt/kvm/kvm_main.c:1333 [inline]
 kvm_vm_ioctl+0x930/0x2530 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3604
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:763 [inline]
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 8700:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x125/0x190 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 kvm_free_memslots arch/x86/kvm/../../../virt/kvm/kvm_main.c:601 [inline]
 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:810 [inline]
 kvm_put_kvm+0xa8d/0xcb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:828
 kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:851
 __fput+0x2ed/0x750 fs/file_table.c:280
 task_work_run+0x147/0x1d0 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:165 [inline]
 prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:196
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff888097b31000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1128 bytes inside of
 2048-byte region [ffff888097b31000, ffff888097b31800)
The buggy address belongs to the page:
page:ffffea00025ecc40 refcount:1 mapcount:0 mapping:00000000499db978 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029ef288 ffffea0002a34408 ffff8880aa400e00
raw: 0000000000000000 ffff888097b31000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888097b31300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888097b31380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888097b31400: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
                                                          ^
 ffff888097b31480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888097b31500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/04/13 00:28 upstream 4f8a3cc1183c 36b0b050 .config console log report syz C ci-upstream-kasan-gce-smack-root
2020/04/21 05:55 upstream ae83d0b416db 98a9f9e6 .config console log report ci-upstream-kasan-gce-smack-root
2020/04/18 11:16 upstream 90280eaa88ac 435c6d53 .config console log report ci-upstream-kasan-gce-smack-root
2020/04/18 07:48 upstream 95988fbc7c31 435c6d53 .config console log report ci-upstream-kasan-gce-smack-root
2020/04/15 16:25 upstream 8632e9b5645b 3f3c5574 .config console log report ci-upstream-kasan-gce-smack-root
2020/04/13 00:06 upstream 4f8a3cc1183c 36b0b050 .config console log report ci-upstream-kasan-gce-smack-root
2020/04/12 23:44 upstream 4f8a3cc1183c 36b0b050 .config console log report ci-upstream-kasan-gce-smack-root
* Struck through repros no longer work on HEAD.