Re: [syzbot] KASAN: use-after-free Read in xfs_qm_dqfree_one

syzbot
2022-12-05T10:35:43Z

syzbot has found a reproducer for the following issue on:

HEAD commit: 0ba09b173387 Revert "mm: align larger anonymous mappings o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15550c47880000
kernel config: https://syzkaller.appspot.com/x/.config?x=2325e409a9a893e1
dashboard link: https://syzkaller.appspot.com/bug?extid=912776840162c13db1a3
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=128c9e23880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9758ec2c06f4/disk-0ba09b17.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/06781dbfd581/vmlinux-0ba09b17.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3d44a22d15fa/bzImage-0ba09b17.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/335889b2d730/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+912776840162c13db1a3@syzkaller.appspotmail.com

XFS (loop1): Quotacheck: Done.
syz-executor.1 (4657): drop_caches: 2
==================================================================
BUG: KASAN: use-after-free in xfs_dquot_type fs/xfs/xfs_dquot.h:136 [inline]
BUG: KASAN: use-after-free in xfs_qm_dqfree_one+0x12f/0x170 fs/xfs/xfs_qm.c:1604
Read of size 1 at addr ffff888079a6aa58 by task syz-executor.1/4657

CPU: 1 PID: 4657 Comm: syz-executor.1 Not tainted 6.1.0-rc7-syzkaller-00211-g0ba09b173387 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
print_address_description+0x74/0x340 mm/kasan/report.c:284
print_report+0x107/0x1f0 mm/kasan/report.c:395
kasan_report+0xcd/0x100 mm/kasan/report.c:495
xfs_dquot_type fs/xfs/xfs_dquot.h:136 [inline]
xfs_qm_dqfree_one+0x12f/0x170 fs/xfs/xfs_qm.c:1604
xfs_qm_shrink_scan+0x351/0x410 fs/xfs/xfs_qm.c:523
do_shrink_slab+0x4e1/0xa00 mm/vmscan.c:842
shrink_slab+0x1e6/0x340 mm/vmscan.c:1002
drop_slab_node mm/vmscan.c:1037 [inline]
drop_slab+0x185/0x2c0 mm/vmscan.c:1047
drop_caches_sysctl_handler+0xb1/0x160 fs/drop_caches.c:66
proc_sys_call_handler+0x576/0x890 fs/proc/proc_sysctl.c:604
do_iter_write+0x6c2/0xc20 fs/read_write.c:861
iter_file_splice_write+0x7fc/0xfc0 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0xe6/0x1c0 fs/splice.c:931
splice_direct_to_actor+0x4e4/0xc00 fs/splice.c:886
do_splice_direct+0x279/0x3d0 fs/splice.c:974
do_sendfile+0x5fb/0xf80 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1317 [inline]
__se_sys_sendfile64+0xd0/0x1b0 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc3e3c8c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc3e4a9a168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fc3e3dabf80 RCX: 00007fc3e3c8c0d9
RDX: 0000000020002080 RSI: 0000000000000004 RDI: 0000000000000006
RBP: 00007fc3e3ce7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000870 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffcb98dc7f R14: 00007fc3e4a9a300 R15: 0000000000022000
</TASK>

Allocated by task 4642:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x3d/0x60 mm/kasan/common.c:52
__kasan_slab_alloc+0x65/0x70 mm/kasan/common.c:325
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slab.h:737 [inline]
slab_alloc_node mm/slub.c:3398 [inline]
slab_alloc mm/slub.c:3406 [inline]
__kmem_cache_alloc_lru mm/slub.c:3413 [inline]
kmem_cache_alloc+0x1cc/0x300 mm/slub.c:3422
kmem_cache_zalloc include/linux/slab.h:679 [inline]
xfs_dquot_alloc+0x36/0x600 fs/xfs/xfs_dquot.c:475
xfs_qm_dqread+0x8a/0x1d0 fs/xfs/xfs_dquot.c:659
xfs_qm_dqget+0x27d/0x4f0 fs/xfs/xfs_dquot.c:870
xfs_qm_vop_dqalloc+0x9bf/0xca0 fs/xfs/xfs_qm.c:1704
xfs_setattr_nonsize+0x3c2/0xfd0 fs/xfs/xfs_iops.c:702
xfs_vn_setattr+0x2f5/0x340 fs/xfs/xfs_iops.c:1022
notify_change+0xe38/0x10f0 fs/attr.c:420
chown_common+0x586/0x8f0 fs/open.c:736
do_fchownat+0x165/0x240 fs/open.c:767
__do_sys_chown fs/open.c:787 [inline]
__se_sys_chown fs/open.c:785 [inline]
__x64_sys_chown+0x7e/0x90 fs/open.c:785
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 3677:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x3d/0x60 mm/kasan/common.c:52
kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:511
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1750
slab_free mm/slub.c:3661 [inline]
kmem_cache_free+0x94/0x1d0 mm/slub.c:3683
xfs_qm_dqpurge+0x4f7/0x660 fs/xfs/xfs_qm.c:177
xfs_qm_dquot_walk+0x249/0x490 fs/xfs/xfs_qm.c:87
xfs_qm_dqpurge_all fs/xfs/xfs_qm.c:193 [inline]
xfs_qm_unmount+0x71/0x100 fs/xfs/xfs_qm.c:205
xfs_unmountfs+0xc5/0x1e0 fs/xfs/xfs_mount.c:1059
xfs_fs_put_super+0x6e/0x2d0 fs/xfs/xfs_super.c:1115
generic_shutdown_super+0x130/0x310 fs/super.c:492
kill_block_super+0x79/0xd0 fs/super.c:1428
deactivate_locked_super+0xa7/0xf0 fs/super.c:332
cleanup_mnt+0x494/0x520 fs/namespace.c:1186
task_work_run+0x243/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0x124/0x150 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:203
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:296
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888079a6aa40
which belongs to the cache xfs_dquot of size 704
The buggy address is located 24 bytes inside of
704-byte region [ffff888079a6aa40, ffff888079a6ad00)

The buggy address belongs to the physical page:
page:ffffea0001e69a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x79a68
head:ffffea0001e69a00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff88814660f000
raw: 0000000000000000 0000000080130013 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 33, tgid 33 (kworker/u4:2), ts 336553992665, free_ts 335702258247
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4291
__alloc_pages+0x259/0x560 mm/page_alloc.c:5558
alloc_slab_page+0xbd/0x190 mm/slub.c:1794
allocate_slab+0x5e/0x4b0 mm/slub.c:1939
new_slab mm/slub.c:1992 [inline]
___slab_alloc+0x782/0xe20 mm/slub.c:3180
__slab_alloc mm/slub.c:3279 [inline]
slab_alloc_node mm/slub.c:3364 [inline]
slab_alloc mm/slub.c:3406 [inline]
__kmem_cache_alloc_lru mm/slub.c:3413 [inline]
kmem_cache_alloc+0x24c/0x300 mm/slub.c:3422
kmem_cache_zalloc include/linux/slab.h:679 [inline]
xfs_dquot_alloc+0x36/0x600 fs/xfs/xfs_dquot.c:475
xfs_qm_dqread+0x8a/0x1d0 fs/xfs/xfs_dquot.c:659
xfs_qm_dqget+0x27d/0x4f0 fs/xfs/xfs_dquot.c:870
xfs_qm_quotacheck_dqadjust+0xb7/0x380 fs/xfs/xfs_qm.c:1077
xfs_qm_dqusage_adjust+0x4bd/0x630 fs/xfs/xfs_qm.c:1189
xfs_iwalk_ag_recs+0x425/0x620 fs/xfs/xfs_iwalk.c:220
xfs_iwalk_run_callbacks+0x20f/0x410 fs/xfs/xfs_iwalk.c:376
xfs_iwalk_ag+0xaa5/0xb80 fs/xfs/xfs_iwalk.c:482
xfs_iwalk_ag_work+0xf5/0x1a0 fs/xfs/xfs_iwalk.c:624
xfs_pwork_work+0x7f/0x180 fs/xfs/xfs_pwork.c:47
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1459 [inline]
free_pcp_prepare+0x80c/0x8f0 mm/page_alloc.c:1509
free_unref_page_prepare mm/page_alloc.c:3387 [inline]
free_unref_page+0x7d/0x5f0 mm/page_alloc.c:3483
__stack_depot_save+0x430/0x4a0 lib/stackdepot.c:506
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x52/0x60 mm/kasan/common.c:52
kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:511
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1750
slab_free mm/slub.c:3661 [inline]
__kmem_cache_free+0x71/0x110 mm/slub.c:3674
memcg_free_slab_cgroups mm/slab.h:456 [inline]
unaccount_slab mm/slab.h:645 [inline]
__free_slab+0xf0/0x320 mm/slub.c:2015
qlist_free_all+0x2b/0x70 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x169/0x180 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x1f/0x70 mm/kasan/common.c:302
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slab.h:737 [inline]
slab_alloc_node mm/slub.c:3398 [inline]
__kmem_cache_alloc_node+0x1d7/0x310 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc+0x9e/0x1a0 mm/slab_common.c:968
kmalloc include/linux/slab.h:558 [inline]
tomoyo_realpath_from_path+0xcd/0x5f0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x227/0x670 security/tomoyo/file.c:822

Memory state around the buggy address:
ffff888079a6a900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888079a6a980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888079a6aa00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ffff888079a6aa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888079a6ab00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================