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

From: syzbot
Date: Mon Aug 02 2021 - 04:49:23 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 4010a528219e Merge tag 'fixes_for_v5.14-rc4' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13611f5c300000
kernel config: https://syzkaller.appspot.com/x/.config?x=1dee114394f7d2c2
dashboard link: https://syzkaller.appspot.com/bug?extid=66e110c312ed4ae684a8
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

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+66e110c312ed4ae684a8@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in timerfd_clock_was_set+0x2b8/0x2e0 fs/timerfd.c:104
Read of size 8 at addr ffff8880140a6cf8 by task syz-executor.2/11068

CPU: 0 PID: 11068 Comm: syz-executor.2 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
print_address_description.constprop.0.cold+0x6c/0x2d6 mm/kasan/report.c:233
__kasan_report mm/kasan/report.c:419 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
timerfd_clock_was_set+0x2b8/0x2e0 fs/timerfd.c:104
timekeeping_inject_offset+0x4af/0x620 kernel/time/timekeeping.c:1375
do_adjtimex+0x28f/0xa30 kernel/time/timekeeping.c:2406
do_clock_adjtime kernel/time/posix-timers.c:1109 [inline]
__do_sys_clock_adjtime+0x163/0x270 kernel/time/posix-timers.c:1121
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2013300188 EFLAGS: 00000246 ORIG_RAX: 0000000000000131
RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000000
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038
R13: 00007ffef0a53bbf R14: 00007f2013300300 R15: 0000000000022000

Allocated by task 1:
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_kmalloc mm/kasan/common.c:513 [inline]
____kasan_kmalloc mm/kasan/common.c:472 [inline]
__kasan_kmalloc+0x98/0xc0 mm/kasan/common.c:522
kasan_kmalloc include/linux/kasan.h:264 [inline]
kmem_cache_alloc_trace+0x1e4/0x480 mm/slab.c:3575
kmalloc include/linux/slab.h:591 [inline]
kzalloc include/linux/slab.h:721 [inline]
__do_sys_timerfd_create+0x265/0x370 fs/timerfd.c:412
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 3306:
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+0xcd/0x100 mm/kasan/common.c:374
kasan_slab_free include/linux/kasan.h:230 [inline]
__cache_free mm/slab.c:3445 [inline]
kfree+0x106/0x2c0 mm/slab.c:3803
kvfree+0x42/0x50 mm/util.c:616
kfree_rcu_work+0x5b7/0x870 kernel/rcu/tree.c:3359
process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xa4/0xd0 mm/kasan/generic.c:348
kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3594
timerfd_release+0x105/0x290 fs/timerfd.c:229
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:209
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xa4/0xd0 mm/kasan/generic.c:348
__call_rcu kernel/rcu/tree.c:3029 [inline]
call_rcu+0xb1/0x750 kernel/rcu/tree.c:3109
inetdev_destroy net/ipv4/devinet.c:328 [inline]
inetdev_event+0xd4c/0x15d0 net/ipv4/devinet.c:1598
notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2123
call_netdevice_notifiers_extack net/core/dev.c:2135 [inline]
call_netdevice_notifiers net/core/dev.c:2149 [inline]
unregister_netdevice_many+0x951/0x1790 net/core/dev.c:11093
ip_tunnel_delete_nets+0x39f/0x5b0 net/ipv4/ip_tunnel.c:1122
ops_exit_list+0x10d/0x160 net/core/net_namespace.c:178
cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:595
process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
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 ffff8880140a6c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 248 bytes inside of
512-byte region [ffff8880140a6c00, ffff8880140a6e00)
The buggy address belongs to the page:
page:ffffea0000502980 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880140a6800 pfn:0x140a6
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea000093cf48 ffffea0000746b08 ffff888010840600
raw: ffff8880140a6800 ffff8880140a6000 0000000100000002 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 0x2c2220(__GFP_HIGH|__GFP_ATOMIC|__GFP_NOWARN|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_THISNODE), pid 8700, ts 180152857573, free_ts 176284490391
prep_new_page mm/page_alloc.c:2436 [inline]
get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4169
__alloc_pages_slowpath.constprop.0+0x2e6/0x21b0 mm/page_alloc.c:4940
__alloc_pages+0x412/0x500 mm/page_alloc.c:5404
__alloc_pages_node include/linux/gfp.h:570 [inline]
kmem_getpages mm/slab.c:1377 [inline]
cache_grow_begin+0x75/0x460 mm/slab.c:2593
cache_alloc_refill+0x27f/0x380 mm/slab.c:2965
____cache_alloc mm/slab.c:3048 [inline]
____cache_alloc mm/slab.c:3031 [inline]
slab_alloc_node mm/slab.c:3249 [inline]
kmem_cache_alloc_node_trace+0x4ca/0x5d0 mm/slab.c:3617
__do_kmalloc_node mm/slab.c:3639 [inline]
__kmalloc_node_track_caller+0x38/0x60 mm/slab.c:3654
kmalloc_reserve net/core/skbuff.c:355 [inline]
__alloc_skb+0xde/0x340 net/core/skbuff.c:426
alloc_skb include/linux/skbuff.h:1112 [inline]
nlmsg_new include/net/netlink.h:953 [inline]
inet6_ifa_notify+0x118/0x220 net/ipv6/addrconf.c:5436
__ipv6_ifa_notify net/ipv6/addrconf.c:6070 [inline]
ipv6_ifa_notify net/ipv6/addrconf.c:6122 [inline]
inet6_addr_add+0x681/0xae0 net/ipv6/addrconf.c:2957
inet6_rtm_newaddr+0xf00/0x1970 net/ipv6/addrconf.c:4871
rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5574
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
sock_sendmsg_nosec net/socket.c:703 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:723
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1346 [inline]
free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1397
free_unref_page_prepare mm/page_alloc.c:3332 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3411
slab_destroy mm/slab.c:1627 [inline]
slabs_destroy+0x89/0xc0 mm/slab.c:1647
cache_flusharray mm/slab.c:3418 [inline]
___cache_free+0x4ba/0x600 mm/slab.c:3480
qlink_free mm/kasan/quarantine.c:146 [inline]
qlist_free_all+0x4e/0x110 mm/kasan/quarantine.c:165
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
__kasan_slab_alloc+0x8b/0xa0 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 mm/slab.c:3323 [inline]
kmem_cache_alloc+0x25f/0x540 mm/slab.c:3507
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:583
kernfs_new_node+0x93/0x120 fs/kernfs/dir.c:645
__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:2435 [inline]
device_add_attrs drivers/base/core.c:2583 [inline]
device_add+0x824/0x2180 drivers/base/core.c:3305

Memory state around the buggy address:
ffff8880140a6b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880140a6c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880140a6c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880140a6d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880140a6d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next in thread: Thomas Gleixner: "Re: [syzbot] KASAN: use-after-free Read in timerfd_clock_was_set"
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