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

syzbot
2021-09-22T06:56:41Z

Hello,

syzbot found the following issue on:

HEAD commit: ddf21bd8ab98 Merge tag 'iov_iter.3-5.15-2021-09-17' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=165c1751300000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d93fe4341f98704
dashboard link: https://syzkaller.appspot.com/bug?extid=ef17b5b364116518fd65
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, 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+ef17b5b364116518fd65@syzkaller.appspotmail.com

usb 4-1: Direct firmware load for ueagle-atm/eagleI.fw failed with error -2
usb 4-1: Falling back to sysfs fallback for: ueagle-atm/eagleI.fw
==================================================================
BUG: KASAN: use-after-free in kernfs_root fs/kernfs/kernfs-internal.h:48 [inline]
BUG: KASAN: use-after-free in kernfs_add_one+0x480/0x4c0 fs/kernfs/dir.c:765
Read of size 8 at addr ffff88801b2ada28 by task kworker/1:4/7907

CPU: 1 PID: 7907 Comm: kworker/1:4 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events request_firmware_work_func
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
kernfs_root fs/kernfs/kernfs-internal.h:48 [inline]
kernfs_add_one+0x480/0x4c0 fs/kernfs/dir.c:765
kernfs_create_dir_ns+0x18b/0x220 fs/kernfs/dir.c:994
sysfs_create_dir_ns+0x128/0x290 fs/sysfs/dir.c:59
create_dir lib/kobject.c:89 [inline]
kobject_add_internal+0x2d2/0xa60 lib/kobject.c:255
kobject_add_varg lib/kobject.c:390 [inline]
kobject_add+0x150/0x1c0 lib/kobject.c:442
device_add+0x36a/0x21b0 drivers/base/core.c:3294
fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:507 [inline]
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:583 [inline]
firmware_fallback_sysfs+0x408/0xe70 drivers/base/firmware_loader/fallback.c:659
_request_firmware+0xbb5/0x1040 drivers/base/firmware_loader/main.c:833
request_firmware_work_func+0xdd/0x230 drivers/base/firmware_loader/main.c:1079
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Allocated by task 7907:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
__kasan_slab_alloc+0x83/0xb0 mm/kasan/common.c:467
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook mm/slab.h:519 [inline]
slab_alloc_node mm/slub.c:3206 [inline]
slab_alloc mm/slub.c:3214 [inline]
kmem_cache_alloc+0x209/0x390 mm/slub.c:3219
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:585
kernfs_new_node fs/kernfs/dir.c:647 [inline]
kernfs_create_dir_ns+0x9c/0x220 fs/kernfs/dir.c:984
sysfs_create_dir_ns+0x128/0x290 fs/sysfs/dir.c:59
create_dir lib/kobject.c:89 [inline]
kobject_add_internal+0x2d2/0xa60 lib/kobject.c:255
kobject_add_varg lib/kobject.c:390 [inline]
kobject_add+0x150/0x1c0 lib/kobject.c:442
device_add+0x36a/0x21b0 drivers/base/core.c:3294
fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:507 [inline]
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:583 [inline]
firmware_fallback_sysfs+0x408/0xe70 drivers/base/firmware_loader/fallback.c:659
_request_firmware+0xbb5/0x1040 drivers/base/firmware_loader/main.c:833
request_firmware_work_func+0xdd/0x230 drivers/base/firmware_loader/main.c:1079
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 69:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free mm/kasan/common.c:328 [inline]
__kasan_slab_free+0xff/0x130 mm/kasan/common.c:374
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1700 [inline]
slab_free_freelist_hook+0x81/0x190 mm/slub.c:1725
slab_free mm/slub.c:3483 [inline]
kmem_cache_free+0x8a/0x5b0 mm/slub.c:3499
kernfs_put.part.0+0x2c4/0x540 fs/kernfs/dir.c:539
kernfs_put+0x42/0x50 fs/kernfs/dir.c:513
__kernfs_remove+0x727/0xab0 fs/kernfs/dir.c:1360
kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1373
sysfs_remove_dir+0xc1/0x100 fs/sysfs/dir.c:102
__kobject_del+0xe2/0x200 lib/kobject.c:620
kobject_del lib/kobject.c:643 [inline]
kobject_del+0x3c/0x60 lib/kobject.c:635
device_del+0x834/0xd60 drivers/base/core.c:3558
usb_disconnect.cold+0x4ba/0x78e drivers/usb/core/hub.c:2251
hub_port_connect drivers/usb/core/hub.c:5199 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5488 [inline]
port_event drivers/usb/core/hub.c:5634 [inline]
hub_event+0x1c9c/0x4330 drivers/usb/core/hub.c:5716
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
process_scheduled_works kernel/workqueue.c:2360 [inline]
worker_thread+0x85c/0x11f0 kernel/workqueue.c:2446
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff88801b2ad9f8
which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 48 bytes inside of
168-byte region [ffff88801b2ad9f8, ffff88801b2adaa0)
The buggy address belongs to the page:
page:ffffea00006cab40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b2ad
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0001cdb480 0000001100000008 ffff888010dc5a00
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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 7198, ts 181519968528, free_ts 181515461864
prep_new_page mm/page_alloc.c:2424 [inline]
get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4153
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5375
alloc_pages+0x1a7/0x300 mm/mempolicy.c:2197
alloc_slab_page mm/slub.c:1763 [inline]
allocate_slab mm/slub.c:1900 [inline]
new_slab+0x319/0x490 mm/slub.c:1963
___slab_alloc+0x921/0xfe0 mm/slub.c:2994
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3081
slab_alloc_node mm/slub.c:3172 [inline]
slab_alloc mm/slub.c:3214 [inline]
kmem_cache_alloc+0x365/0x390 mm/slub.c:3219
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:585
kernfs_new_node+0x93/0x120 fs/kernfs/dir.c:647
__kernfs_create_file+0x51/0x350 fs/kernfs/file.c:985
sysfs_add_file_mode_ns+0x226/0x540 fs/sysfs/file.c:317
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x328/0xb20 fs/sysfs/group.c:149
netdev_queue_add_kobject net/core/net-sysfs.c:1616 [inline]
netdev_queue_update_kobjects+0x353/0x460 net/core/net-sysfs.c:1655
register_queue_kobjects net/core/net-sysfs.c:1716 [inline]
netdev_register_kobject+0x35a/0x430 net/core/net-sysfs.c:1959
register_netdevice+0xd33/0x1500 net/core/dev.c:10295
veth_newlink+0x58c/0xb20 drivers/net/veth.c:1726
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1338 [inline]
free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1389
free_unref_page_prepare mm/page_alloc.c:3315 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3394
__unfreeze_partials+0x340/0x360 mm/slub.c:2495
qlink_free mm/kasan/quarantine.c:146 [inline]
qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
__kasan_slab_alloc+0x95/0xb0 mm/kasan/common.c:444
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook mm/slab.h:519 [inline]
slab_alloc_node mm/slub.c:3206 [inline]
slab_alloc mm/slub.c:3214 [inline]
kmem_cache_alloc+0x209/0x390 mm/slub.c:3219
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:585
kernfs_new_node+0x93/0x120 fs/kernfs/dir.c:647
__kernfs_create_file+0x51/0x350 fs/kernfs/file.c:985
sysfs_add_file_mode_ns+0x226/0x540 fs/sysfs/file.c:317
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x328/0xb20 fs/sysfs/group.c:149
internal_create_groups.part.0+0x90/0x140 fs/sysfs/group.c:189
internal_create_groups fs/sysfs/group.c:185 [inline]
sysfs_create_groups+0x25/0x50 fs/sysfs/group.c:215
device_add_groups drivers/base/core.c:2438 [inline]
device_add_attrs drivers/base/core.c:2597 [inline]
device_add+0x14ee/0x21b0 drivers/base/core.c:3310
netdev_register_kobject+0x181/0x430 net/core/net-sysfs.c:1955

Memory state around the buggy address:
ffff88801b2ad900: fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801b2ad980: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fa
>ffff88801b2ada00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801b2ada80: fb fb fb fb fc fc fc fc fc fc fc fc 00 00 00 00
ffff88801b2adb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

---
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