[syzbot] KASAN: slab-out-of-bounds Read in hfs_cat_keycmp

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3a28c2c89f4b Merge tag 'unsigned-char-6.2-for-linus' of gi..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12253e3b880000
kernel config: https://syzkaller.appspot.com/x/.config?x=f3de84cba2ef4a23
dashboard link: https://syzkaller.appspot.com/bug?extid=883fa6a25abf9dd035ef
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1261813b880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=114306af880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9374b222f430/disk-3a28c2c8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/161c182658ff/vmlinux-3a28c2c8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/da0159b90f5a/bzImage-3a28c2c8.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/07b3c29e7ecc/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+883fa6...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in hfs_strcmp+0x147/0x170 fs/hfs/string.c:84
Read of size 1 at addr ffff8880204501ce by task kworker/u4:5/1091

CPU: 0 PID: 1091 Comm: kworker/u4:5 Not tainted 6.1.0-syzkaller-00071-g3a28c2c89f4b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:395
kasan_report+0xbf/0x1f0 mm/kasan/report.c:495
hfs_strcmp+0x147/0x170 fs/hfs/string.c:84
hfs_cat_keycmp+0x17d/0x1d0 fs/hfs/catalog.c:181
__hfs_brec_find+0x1d0/0x4d0 fs/hfs/bfind.c:75
hfs_brec_find+0x202/0x4e0 fs/hfs/bfind.c:138
hfs_write_inode+0x349/0x980 fs/hfs/inode.c:462
write_inode fs/fs-writeback.c:1440 [inline]
__writeback_single_inode+0xcfc/0x1440 fs/fs-writeback.c:1652
writeback_sb_inodes+0x54d/0xf90 fs/fs-writeback.c:1878
wb_writeback+0x2c5/0xd70 fs/fs-writeback.c:2052
wb_do_writeback fs/fs-writeback.c:2195 [inline]
wb_workfn+0x2e0/0x12f0 fs/fs-writeback.c:2235
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>

Allocated by task 1091:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa5/0xb0 mm/kasan/common.c:380
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slab_common.c:955 [inline]
__kmalloc+0x5a/0xd0 mm/slab_common.c:968
kmalloc include/linux/slab.h:569 [inline]
hfs_find_init+0x95/0x240 fs/hfs/bfind.c:21
hfs_write_inode+0x225/0x980 fs/hfs/inode.c:457
write_inode fs/fs-writeback.c:1440 [inline]
__writeback_single_inode+0xcfc/0x1440 fs/fs-writeback.c:1652
writeback_sb_inodes+0x54d/0xf90 fs/fs-writeback.c:1878
wb_writeback+0x2c5/0xd70 fs/fs-writeback.c:2052
wb_do_writeback fs/fs-writeback.c:2195 [inline]
wb_workfn+0x2e0/0x12f0 fs/fs-writeback.c:2235
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

The buggy address belongs to the object at ffff888020450180
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 78 bytes inside of
96-byte region [ffff888020450180, ffff8880204501e0)

The buggy address belongs to the physical page:
page:ffffea0000811400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x20450
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00005f3e40 dead000000000002 ffff888012041780
raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 9, tgid 9 (kworker/u4:0), ts 7013039595, free_ts 7011439514
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4291
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5558
alloc_pages+0x1aa/0x270 mm/mempolicy.c:2285
alloc_slab_page mm/slub.c:1794 [inline]
allocate_slab+0x25f/0x350 mm/slub.c:1939
new_slab mm/slub.c:1992 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3180
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279
slab_alloc_node mm/slub.c:3364 [inline]
__kmem_cache_alloc_node+0x199/0x3e0 mm/slub.c:3437
kmalloc_trace+0x26/0x60 mm/slab_common.c:1045
kmalloc include/linux/slab.h:564 [inline]
kzalloc include/linux/slab.h:700 [inline]
blk_mq_alloc_ctxs block/blk-mq.c:3921 [inline]
blk_mq_init_allocated_queue+0x1ad/0x1470 block/blk-mq.c:4162
blk_mq_init_queue_data block/blk-mq.c:3982 [inline]
blk_mq_init_queue+0xc7/0x150 block/blk-mq.c:3992
scsi_alloc_sdev+0x852/0xd90 drivers/scsi/scsi_scan.c:335
scsi_probe_and_add_lun+0x208b/0x34d0 drivers/scsi/scsi_scan.c:1183
__scsi_scan_target+0x21f/0xda0 drivers/scsi/scsi_scan.c:1665
scsi_scan_channel drivers/scsi/scsi_scan.c:1753 [inline]
scsi_scan_channel+0x148/0x1e0 drivers/scsi/scsi_scan.c:1729
scsi_scan_host_selected+0x2e3/0x3b0 drivers/scsi/scsi_scan.c:1782
do_scsi_scan_host+0x1e8/0x260 drivers/scsi/scsi_scan.c:1921
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+0x65c/0xd90 mm/page_alloc.c:1509
free_unref_page_prepare mm/page_alloc.c:3387 [inline]
free_unref_page_list+0x176/0xc40 mm/page_alloc.c:3529
release_pages+0xc8a/0x1360 mm/swap.c:1055
tlb_batch_pages_flush+0xa8/0x1a0 mm/mmu_gather.c:59
tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
tlb_flush_mmu mm/mmu_gather.c:261 [inline]
tlb_finish_mmu+0x14b/0x7e0 mm/mmu_gather.c:361
exit_mmap+0x202/0x7b0 mm/mmap.c:3096
__mmput+0x128/0x4c0 kernel/fork.c:1185
mmput+0x60/0x70 kernel/fork.c:1207
free_bprm+0x65/0x2e0 fs/exec.c:1486
kernel_execve+0x3fe/0x500 fs/exec.c:2004
call_usermodehelper_exec_async+0x2e7/0x580 kernel/umh.c:113
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Memory state around the buggy address:
ffff888020450080: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888020450100: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff888020450180: 00 00 00 00 00 00 00 00 00 06 fc fc fc fc fc fc
^
ffff888020450200: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888020450280: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit c53ed55cb275344086e32a7080a6b19cb183650b
Author: ZhangPeng <zhangp...@huawei.com>
Date: Fri Dec 2 03:00:38 2022 +0000

hfs: Fix OOB Write in hfs_asc2mac

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13294485480000
start commit: 3a28c2c89f4b Merge tag 'unsigned-char-6.2-for-linus' of gi..
git tree: upstream

kernel config: https://syzkaller.appspot.com/x/.config?x=f3de84cba2ef4a23
dashboard link: https://syzkaller.appspot.com/bug?extid=883fa6a25abf9dd035ef

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1261813b880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=114306af880000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: hfs: Fix OOB Write in hfs_asc2mac

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Dmitry Vyukov]

Hard to say if it's the fix or not, bisection diverged due to an
unrelated kernel bug. But this bug is probably fixed as well, so
without having a better candidate, let's close the report: