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KASAN: use-after-free Read in xfs_inobt_init_key_from_rec

Status: fixed on 2018/07/09 18:05
Subsystems: xfs
[Documentation on labels]
Reported-by: syzbot+08ab33be0178b76851c8@syzkaller.appspotmail.com
Fix commit: 2e050e648ad6 xfs: fix inobt magic number check
First crash: 2212d, last: 2212d
Discussions (2)
Title Replies (including bot) Last reply
[PATCH 4.17 00/67] 4.17.7-stable review 74 (74) 2018/07/17 09:41
KASAN: use-after-free Read in xfs_inobt_init_key_from_rec 0 (1) 2018/04/03 17:01

Sample crash report:
XFS (loop0): Mounting V4 Filesystem
XFS (loop0): totally zeroed log
==================================================================
BUG: KASAN: use-after-free in xfs_inobt_init_key_from_rec+0x6a/0x70 fs/xfs/libxfs/xfs_ialloc_btree.c:195
Read of size 4 at addr ffff8801af98cf00 by task syzkaller185183/4464

CPU: 0 PID: 4464 Comm: syzkaller185183 Not tainted 4.16.0+ #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1a7/0x27d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 xfs_inobt_init_key_from_rec+0x6a/0x70 fs/xfs/libxfs/xfs_ialloc_btree.c:195
 xfs_lookup_get_search_key+0x7e/0xc0 fs/xfs/libxfs/xfs_btree.c:1858
 xfs_btree_lookup+0x932/0x1180 fs/xfs/libxfs/xfs_btree.c:1948
 xfs_inobt_lookup fs/xfs/libxfs/xfs_ialloc.c:75 [inline]
 xfs_imap_lookup+0x216/0x640 fs/xfs/libxfs/xfs_ialloc.c:2235
 xfs_imap+0x78f/0x960 fs/xfs/libxfs/xfs_ialloc.c:2364
 xfs_iread+0xc7/0x770 fs/xfs/libxfs/xfs_inode_buf.c:556
 xfs_iget_cache_miss fs/xfs/xfs_icache.c:475 [inline]
 xfs_iget+0xcec/0x3060 fs/xfs/xfs_icache.c:626
 xfs_mountfs+0x139a/0x2690 fs/xfs/xfs_mount.c:881
 xfs_fs_fill_super+0xc8d/0x1250 fs/xfs/xfs_super.c:1703
 mount_bdev+0x2b7/0x370 fs/super.c:1119
 xfs_fs_mount+0x34/0x40 fs/xfs/xfs_super.c:1770
 mount_fs+0x66/0x2d0 fs/super.c:1222
 vfs_kern_mount.part.26+0xc6/0x4a0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:2514 [inline]
 do_new_mount fs/namespace.c:2517 [inline]
 do_mount+0xea4/0x2b90 fs/namespace.c:2847
 ksys_mount+0xab/0x120 fs/namespace.c:3063
 SYSC_mount fs/namespace.c:3077 [inline]
 SyS_mount+0x39/0x50 fs/namespace.c:3074
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44371a
RSP: 002b:00007fff43e464c8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000840 RCX: 000000000044371a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fff43e464d0
RBP: 0000000000000003 R08: 0000000020018900 R09: 000000000000000a
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004
R13: 0000000000402610 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4462:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542
 getname_flags+0xcb/0x580 fs/namei.c:138
 getname+0x19/0x20 fs/namei.c:209
 do_sys_open+0x2e7/0x6d0 fs/open.c:1095
 SYSC_open fs/open.c:1119 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1114
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 4462:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3486 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3744
 putname+0xee/0x130 fs/namei.c:258
 do_sys_open+0x31b/0x6d0 fs/open.c:1110
 SYSC_open fs/open.c:1119 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1114
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801af98c600
 which belongs to the cache names_cache of size 4096
The buggy address is located 2304 bytes inside of
 4096-byte region [ffff8801af98c600, ffff8801af98d600)
The buggy address belongs to the page:
page:ffffea0006be6300 count:1 mapcount:0 mapping:ffff8801af98c600 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801af98c600 0000000000000000 0000000100000001
raw: ffffea0006be7aa0 ffffea0006be5f20 ffff8801da5ea600 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801af98ce00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801af98ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801af98cf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801af98cf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801af98d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/04/03 15:32 upstream 642e7fd23353 676bd07e .config console log report syz C ci-upstream-kasan-gce-root
* Struck through repros no longer work on HEAD.