[syzbot] KASAN: use-after-free Read in kernfs_activate

From: syzbot
Date: Sat Mar 05 2022 - 12:08:27 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 719fce7539cd Merge tag 'soc-fixes-5.17-2' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15240076700000
kernel config: https://syzkaller.appspot.com/x/.config?x=66c6970b31a1a2ff
dashboard link: https://syzkaller.appspot.com/bug?extid=82240fa5f8dffe45d4f1
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+82240fa5f8dffe45d4f1@xxxxxxxxxxxxxxxxxxxxxxxxx

usb 1-1: Falling back to sysfs fallback for: ueagle-atm/eagleII.fw
==================================================================
BUG: KASAN: use-after-free in kernfs_root fs/kernfs/kernfs-internal.h:48 [inline]
BUG: KASAN: use-after-free in kernfs_next_descendant_post fs/kernfs/dir.c:1272 [inline]
BUG: KASAN: use-after-free in kernfs_activate+0xef/0x520 fs/kernfs/dir.c:1312
Read of size 8 at addr ffff88802e502118 by task kworker/0:9/14749

CPU: 0 PID: 14749 Comm: kworker/0:9 Not tainted 5.17.0-rc6-syzkaller-00046-g719fce7539cd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events request_firmware_work_func
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
print_address_description+0x65/0x3a0 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report+0x19a/0x1f0 mm/kasan/report.c:459
kernfs_root fs/kernfs/kernfs-internal.h:48 [inline]
kernfs_next_descendant_post fs/kernfs/dir.c:1272 [inline]
kernfs_activate+0xef/0x520 fs/kernfs/dir.c:1312
kernfs_add_one+0x56c/0x6d0 fs/kernfs/dir.c:767
kernfs_create_dir_ns+0x1bf/0x220 fs/kernfs/dir.c:1004
sysfs_create_dir_ns+0x181/0x390 fs/sysfs/dir.c:59
create_dir lib/kobject.c:89 [inline]
kobject_add_internal+0x418/0xb50 lib/kobject.c:255
kobject_add_varg lib/kobject.c:390 [inline]
kobject_add+0x14c/0x210 lib/kobject.c:442
class_dir_create_and_add drivers/base/core.c:2942 [inline]
get_device_parent+0x3d5/0x430 drivers/base/core.c:2997
device_add+0x3b7/0x16d0 drivers/base/core.c:3326
fw_load_sysfs_fallback+0xd2/0x7d0 drivers/base/firmware_loader/fallback.c:512
fw_load_from_user_helper+0x242/0x320 drivers/base/firmware_loader/fallback.c:588
_request_firmware+0x3b9/0x670 drivers/base/firmware_loader/main.c:774
request_firmware_work_func+0x128/0x270 drivers/base/firmware_loader/main.c:1020
process_one_work+0x86c/0x1190 kernel/workqueue.c:2307
worker_thread+0xab1/0x1300 kernel/workqueue.c:2454
kthread+0x2a3/0x2d0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30
</TASK>

Allocated by task 14749:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
__kasan_slab_alloc+0xb2/0xe0 mm/kasan/common.c:469
kasan_slab_alloc include/linux/kasan.h:260 [inline]
slab_post_alloc_hook mm/slab.h:732 [inline]
slab_alloc_node mm/slub.c:3230 [inline]
slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc+0x1c9/0x310 mm/slub.c:3243
kmem_cache_zalloc include/linux/slab.h:704 [inline]
__kernfs_new_node+0xdb/0x720 fs/kernfs/dir.c:585
kernfs_new_node fs/kernfs/dir.c:647 [inline]
kernfs_create_dir_ns+0x90/0x220 fs/kernfs/dir.c:994
sysfs_create_dir_ns+0x181/0x390 fs/sysfs/dir.c:59
create_dir lib/kobject.c:89 [inline]
kobject_add_internal+0x418/0xb50 lib/kobject.c:255
kobject_add_varg lib/kobject.c:390 [inline]
kobject_add+0x14c/0x210 lib/kobject.c:442
class_dir_create_and_add drivers/base/core.c:2942 [inline]
get_device_parent+0x3d5/0x430 drivers/base/core.c:2997
device_add+0x3b7/0x16d0 drivers/base/core.c:3326
fw_load_sysfs_fallback+0xd2/0x7d0 drivers/base/firmware_loader/fallback.c:512
fw_load_from_user_helper+0x242/0x320 drivers/base/firmware_loader/fallback.c:588
_request_firmware+0x3b9/0x670 drivers/base/firmware_loader/main.c:774
request_firmware_work_func+0x128/0x270 drivers/base/firmware_loader/main.c:1020
process_one_work+0x86c/0x1190 kernel/workqueue.c:2307
worker_thread+0xab1/0x1300 kernel/workqueue.c:2454
kthread+0x2a3/0x2d0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30

Freed by task 14455:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4c/0x70 mm/kasan/common.c:45
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x126/0x180 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:236 [inline]
slab_free_hook mm/slub.c:1728 [inline]
slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1754
slab_free mm/slub.c:3509 [inline]
kmem_cache_free+0xb6/0x1c0 mm/slub.c:3526
kernfs_put+0x340/0x490 fs/kernfs/dir.c:539
__kernfs_remove+0xe80/0x1150 fs/kernfs/dir.c:1388
kernfs_remove+0x6c/0x80 fs/kernfs/dir.c:1403
__kobject_del+0xcc/0x310 lib/kobject.c:620
kobject_del+0x41/0x60 lib/kobject.c:643
device_del+0xa1e/0xbf0 drivers/base/core.c:3603
usb_disconnect+0x56f/0x8a0 drivers/usb/core/hub.c:2254
hub_port_connect+0x29c/0x2910 drivers/usb/core/hub.c:5202
hub_port_connect_change+0x5f9/0xc20 drivers/usb/core/hub.c:5502
port_event+0xca0/0x13e0 drivers/usb/core/hub.c:5660
hub_event+0x4ed/0xe40 drivers/usb/core/hub.c:5742
process_one_work+0x86c/0x1190 kernel/workqueue.c:2307
process_scheduled_works kernel/workqueue.c:2370 [inline]
worker_thread+0xe18/0x1300 kernel/workqueue.c:2456
kthread+0x2a3/0x2d0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30

The buggy address belongs to the object at ffff88802e5020e8
which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 48 bytes inside of
168-byte region [ffff88802e5020e8, ffff88802e502190)
The buggy address belongs to the page:
page:ffffea0000b94080 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2e502
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff888140007b40
raw: 0000000000000000 0000000080110011 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 14455, ts 555782168656, free_ts 555704660304
prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0x729/0x9e0 mm/page_alloc.c:4165
__alloc_pages+0x255/0x580 mm/page_alloc.c:5389
alloc_slab_page mm/slub.c:1799 [inline]
allocate_slab+0xce/0x3f0 mm/slub.c:1944
new_slab mm/slub.c:2004 [inline]
___slab_alloc+0x3fe/0xc30 mm/slub.c:3018
__slab_alloc mm/slub.c:3105 [inline]
slab_alloc_node mm/slub.c:3196 [inline]
slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc+0x276/0x310 mm/slub.c:3243
kmem_cache_zalloc include/linux/slab.h:704 [inline]
__kernfs_new_node+0xdb/0x720 fs/kernfs/dir.c:585
kernfs_new_node+0x95/0x160 fs/kernfs/dir.c:647
__kernfs_create_file+0x45/0x2e0 fs/kernfs/file.c:987
sysfs_add_file_mode_ns+0x21d/0x330 fs/sysfs/file.c:294
sysfs_merge_group+0x1ff/0x430 fs/sysfs/group.c:342
dpm_sysfs_add+0xbd/0x260 drivers/base/power/sysfs.c:707
device_add+0xe2c/0x16d0 drivers/base/core.c:3362
usb_create_ep_devs+0x12e/0x240 drivers/usb/core/endpoint.c:169
usb_new_device+0x117c/0x1940 drivers/usb/core/hub.c:2594
hub_port_connect+0x100b/0x2910 drivers/usb/core/hub.c:5358
hub_port_connect_change+0x5f9/0xc20 drivers/usb/core/hub.c:5502
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1352 [inline]
free_pcp_prepare+0xd1c/0xe00 mm/page_alloc.c:1404
free_unref_page_prepare mm/page_alloc.c:3325 [inline]
free_unref_page+0x7d/0x580 mm/page_alloc.c:3404
do_slab_free mm/slub.c:3497 [inline]
___cache_free+0x107/0x160 mm/slub.c:3516
qlist_free_all mm/kasan/quarantine.c:176 [inline]
kasan_quarantine_reduce+0x169/0x1f0 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:446
kasan_slab_alloc include/linux/kasan.h:260 [inline]
slab_post_alloc_hook mm/slab.h:732 [inline]
slab_alloc_node mm/slub.c:3230 [inline]
__kmalloc_node+0x21f/0x420 mm/slub.c:4468
kmalloc_node include/linux/slab.h:604 [inline]
kvmalloc_node+0x6e/0xe0 mm/util.c:580
kvmalloc include/linux/slab.h:731 [inline]
seq_buf_alloc fs/seq_file.c:38 [inline]
seq_read_iter+0x1f6/0xd30 fs/seq_file.c:210
call_read_iter include/linux/fs.h:2068 [inline]
new_sync_read fs/read_write.c:400 [inline]
vfs_read+0xaf9/0xe60 fs/read_write.c:481
ksys_read+0x18f/0x2c0 fs/read_write.c:619
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
ffff88802e502000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802e502080: fb fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb
>ffff88802e502100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802e502180: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802e502200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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Next message: Trond Myklebust: "Re: [PATCH -next 2/2] nfs: nfs_file_write() check writeback errors correctly"
Previous message: Jason A. Donenfeld: "Re: [PATCH printk v1 03/13] printk: use percpu flag instead of cpu_online()"
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