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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 09688c0166e7 Linux 5.17-rc8
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11b42729700000
kernel config: https://syzkaller.appspot.com/x/.config?x=6da459dcfde3b8d0
dashboard link: https://syzkaller.appspot.com/bug?extid=97a16334dbd58916f7fb
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+97a163...@syzkaller.appspotmail.com

usb 1-1: Direct firmware load for ueagle-atm/adi930.fw failed with error -2
usb 1-1: Falling back to sysfs fallback for: ueagle-atm/adi930.fw
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in kernfs_get+0x1c/0x90 fs/kernfs/dir.c:496
Read of size 4 at addr ffff88801ded39f8 by task kworker/1:2/2510

CPU: 1 PID: 2510 Comm: kworker/1:2 Not tainted 5.17.0-rc8-syzkaller #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
kasan_check_range+0x2b5/0x2f0 mm/kasan/generic.c:189
instrument_atomic_read include/linux/instrumented.h:71 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
kernfs_get+0x1c/0x90 fs/kernfs/dir.c:496
sysfs_get include/linux/sysfs.h:635 [inline]
create_dir lib/kobject.c:111 [inline]
kobject_add_internal+0x5e5/0xb50 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 2510:
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 7376:
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 ffff88801ded39f8
which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 0 bytes inside of
168-byte region [ffff88801ded39f8, ffff88801ded3aa0)
The buggy address belongs to the page:
page:ffffea000077b4c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1ded3
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0001d9dd80 dead000000000002 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 3627, ts 120049121188, free_ts 120016924446
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
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x54c/0xed0 fs/sysfs/group.c:148
internal_create_groups fs/sysfs/group.c:188 [inline]
sysfs_create_groups+0x5d/0x130 fs/sysfs/group.c:214
create_dir lib/kobject.c:100 [inline]
kobject_add_internal+0x5a1/0xb50 lib/kobject.c:255
kobject_add_varg lib/kobject.c:390 [inline]
kobject_init_and_add+0x123/0x190 lib/kobject.c:473
netdev_queue_add_kobject net/core/net-sysfs.c:1653 [inline]
netdev_queue_update_kobjects+0x214/0x4c0 net/core/net-sysfs.c:1705
register_queue_kobjects net/core/net-sysfs.c:1766 [inline]
netdev_register_kobject+0x263/0x310 net/core/net-sysfs.c:2012
register_netdevice+0x127a/0x1c00 net/core/dev.c:9667
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
free_slab mm/slub.c:2043 [inline]
discard_slab mm/slub.c:2049 [inline]
__unfreeze_partials+0x1ab/0x200 mm/slub.c:2536
put_cpu_partial+0x116/0x180 mm/slub.c:2612
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]
kmem_cache_alloc_node+0x201/0x370 mm/slub.c:3266
__alloc_skb+0xd8/0x5a0 net/core/skbuff.c:414
alloc_skb include/linux/skbuff.h:1158 [inline]
nlmsg_new include/net/netlink.h:953 [inline]
rtmsg_ifinfo_build_skb+0x81/0x190 net/core/rtnetlink.c:3833
rtmsg_ifinfo_event net/core/rtnetlink.c:3869 [inline]
rtnetlink_event+0xed/0x1b0 net/core/rtnetlink.c:5647
notifier_call_chain kernel/notifier.c:84 [inline]
raw_notifier_call_chain+0xe7/0x170 kernel/notifier.c:392
call_netdevice_notifiers_info net/core/dev.c:1919 [inline]
netdev_lower_state_changed+0x1a4/0x250 net/core/dev.c:7894
team_lower_state_changed drivers/net/team/team.c:89 [inline]
team_refresh_port_linkup drivers/net/team/team.c:99 [inline]
__team_port_change_send+0x20b/0x5a0 drivers/net/team/team.c:2902
__team_port_change_check drivers/net/team/team.c:2949 [inline]
team_port_change_check+0x9c/0x210 drivers/net/team/team.c:2971
team_device_event+0x388/0x410 drivers/net/team/team.c:3000

Memory state around the buggy address:
ffff88801ded3880: fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc
ffff88801ded3900: fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801ded3980: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fa
^
ffff88801ded3a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801ded3a80: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb
==================================================================


---
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[Tejun Heo]

On Mon, Mar 14, 2022 at 06:49:19AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 09688c0166e7 Linux 5.17-rc8
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11b42729700000
> kernel config: https://syzkaller.appspot.com/x/.config?x=6da459dcfde3b8d0
> dashboard link: https://syzkaller.appspot.com/bug?extid=97a16334dbd58916f7fb
> 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+97a163...@syzkaller.appspotmail.com
>
> usb 1-1: Direct firmware load for ueagle-atm/adi930.fw failed with error -2
> usb 1-1: Falling back to sysfs fallback for: ueagle-atm/adi930.fw
> ==================================================================
> BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
> BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
> BUG: KASAN: use-after-free in kernfs_get+0x1c/0x90 fs/kernfs/dir.c:496
> Read of size 4 at addr ffff88801ded39f8 by task kworker/1:2/2510

Looks like firmware loading and usb hub removal racing? I'm not sure there's
whole lot we can do from the kernfs side. Greg?

Thanks.

--
tejun

[Greg KH]

Odd. Let me look at it. If syzbot is starting to poke at ATM drivers,
wow, lots of issues are going to start falling out...

thanks,

greg k-h

[Hillf Danton]

On Mon, 14 Mar 2022 06:49:19 -0700

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 09688c0166e7 Linux 5.17-rc8
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11b42729700000
> kernel config: https://syzkaller.appspot.com/x/.config?x=6da459dcfde3b8d0
> dashboard link: https://syzkaller.appspot.com/bug?extid=97a16334dbd58916f7fb
> 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+97a163...@syzkaller.appspotmail.com
>
> usb 1-1: Direct firmware load for ueagle-atm/adi930.fw failed with error -2
> usb 1-1: Falling back to sysfs fallback for: ueagle-atm/adi930.fw
> ==================================================================
> BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
> BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
> BUG: KASAN: use-after-free in kernfs_get+0x1c/0x90 fs/kernfs/dir.c:496
> Read of size 4 at addr ffff88801ded39f8 by task kworker/1:2/2510

Similar uaf was reported. [1]

Attempted fix - get kerfs node before kernfs_add_one() and the caller of
kernfs_create_dir_ns() is responsible for putting it after kernfs_remove().

Only for thoughts now.

Hillf

[1] https://lore.kernel.org/lkml/000000000000ad...@google.com/

--- y/fs/kernfs/dir.c
+++ x/fs/kernfs/dir.c
@@ -1000,12 +1000,17 @@ struct kernfs_node *kernfs_create_dir_ns
kn->ns = ns;
kn->priv = priv;

+ /* hold another grab to kn to make kernfs_activate() safe and
+ * caller is responsible for putting kn after kernfs_remove()
+ */
+ kernfs_get(kn);
/* link in */
rc = kernfs_add_one(kn);
if (!rc)
return kn;

- kernfs_put(kn);
+ kernfs_put(kn); /* for get */
+ kernfs_put(kn); /* for new node */
return ERR_PTR(rc);
}

--- y/fs/sysfs/dir.c
+++ x/fs/sysfs/dir.c
@@ -99,6 +99,7 @@ void sysfs_remove_dir(struct kobject *ko
if (kn) {
WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
kernfs_remove(kn);
+ kernfs_put(kn);
}
}

--- y/fs/sysfs/group.c
+++ x/fs/sysfs/group.c
@@ -147,8 +147,10 @@ static int internal_create_group(struct
kernfs_get(kn);
error = create_files(kn, kobj, uid, gid, grp, update);
if (error) {
- if (grp->name)
+ if (grp->name) {
kernfs_remove(kn);
+ kernfs_put(kn);
+ }
}
kernfs_put(kn);

@@ -286,8 +288,10 @@ void sysfs_remove_group(struct kobject *
}

remove_files(kn, grp);
- if (grp->name)
+ if (grp->name) {
kernfs_remove(kn);
+ kernfs_put(kn);
+ }

kernfs_put(kn);
}

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.