syzbot


KASAN: stack-out-of-bounds Read in fixup_exception

Status: auto-closed as invalid on 2019/02/22 10:26
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+fca9eb37032df9db192b@syzkaller.appspotmail.com
First crash: 2131d, last: 2131d

Sample crash report:
==================================================================
BUG: KASAN: stack-out-of-bounds in fixup_exception+0xc6/0xcb arch/x86/mm/extable.c:192
Read of size 8 at addr ffff8801b36c7328 by task syz-executor2/10886

CPU: 0 PID: 10886 Comm: syz-executor2 Not tainted 4.18.0-rc1+ #115
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+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 fixup_exception+0xc6/0xcb arch/x86/mm/extable.c:192
 no_context+0x9d/0x980 arch/x86/mm/fault.c:720
 __bad_area_nosemaphore+0x33b/0x3f0 arch/x86/mm/fault.c:909
 bad_area_nosemaphore+0x33/0x40 arch/x86/mm/fault.c:916
 __do_page_fault+0x1db/0xe50 arch/x86/mm/fault.c:1335
 do_page_fault+0xf6/0x8c0 arch/x86/mm/fault.c:1478
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1160
RIP: 0010:vmx_vcpu_run+0x124a/0x2600 arch/x86/kvm/vmx.c:10022
Code: a9 68 03 00 00 4c 8b b1 70 03 00 00 4c 8b b9 78 03 00 00 48 8b 89 08 03 00 00 75 05 0f 01 c2 eb 03 0f 01 c3 48 89 4c 24 08 59 <0f> 96 81 88 56 00 00 48 89 81 00 03 00 00 48 89 99 18 03 00 00 8f 
RSP: 0018:ffff8801b36c7358 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 1ffff10039f114e9 RSI: 0000000000000000 RDI: ffffffff88f1b020
RBP: ffff8801b36c73e8 R08: 0000000000000001 R09: 0000000000000001
R10: ffffed003b5c46d6 R11: 0000000000000001 R12: 0000000000000001
R13: ffff8801cf88a748 R14: ffff8801d6922380 R15: 0000000000000002
 lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924
 seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline]
 read_seqcount_begin include/linux/seqlock.h:164 [inline]
 set_root+0x198/0x820 fs/namei.c:818
 path_init+0xc99/0x2340 fs/namei.c:2164
 path_openat+0x1f9/0x4e10 fs/namei.c:3534
 do_filp_open+0x255/0x380 fs/namei.c:3574
 do_sys_open+0x584/0x760 fs/open.c:1101
 __do_sys_openat fs/open.c:1128 [inline]
 __se_sys_openat fs/open.c:1122 [inline]
 __x64_sys_openat+0x9d/0x100 fs/open.c:1122
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a99
Code: 1d ba 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 b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007f39e6bd6c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f39e6bd76d4 RCX: 0000000000455a99
RDX: 0000000000000000 RSI: 0000000020000380 RDI: ffffffffffffff9c
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004c02b6 R14: 00000000004cfa08 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006cdb1c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 ffffea0006cdb008 ffffea0006cdb188 0000000000000000
raw: 0000000000000000 ffff8801b36c7000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801b36c7200: f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2 f2 f2
 ffff8801b36c7280: 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2
>ffff8801b36c7300: 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2
                                  ^
 ffff8801b36c7380: 00 f2 f2 f2 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801b36c7400: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2 f2
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/06/24 11:08 upstream 77072ca59fdd 2064fc5c .config console log report ci-upstream-kasan-gce
* Struck through repros no longer work on HEAD.