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Subject[syzbot] KASAN: use-after-free Read in kill_fasync
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Hello,

syzbot found the following issue on:

HEAD commit: cb71b93c2dc3 Add linux-next specific files for 20220628
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13a297cc080000
kernel config: https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
dashboard link: https://syzkaller.appspot.com/bug?extid=382c8824777dca2812fe
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=115fdbec080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132e4c92080000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15a3c0a4080000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17a3c0a4080000
console output: https://syzkaller.appspot.com/x/log.txt?x=13a3c0a4080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+382c8824777dca2812fe@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in kill_fasync+0x45e/0x470 fs/fcntl.c:1014
Read of size 8 at addr ffff88807dc93168 by task kworker/0:2/144

CPU: 0 PID: 144 Comm: kworker/0:2 Not tainted 5.19.0-rc4-next-20220628-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Workqueue: events key_garbage_collector
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
kill_fasync+0x45e/0x470 fs/fcntl.c:1014
post_one_notification.isra.0+0x6e4/0x990 kernel/watch_queue.c:128
remove_watch_from_object+0x35a/0x9d0 kernel/watch_queue.c:527
remove_watch_list include/linux/watch_queue.h:115 [inline]
key_gc_unused_keys.constprop.0+0x2e5/0x600 security/keys/gc.c:135
key_garbage_collector+0x3d7/0x920 security/keys/gc.c:297
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
</TASK>

Allocated by task 5494:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
alloc_pipe_info+0x105/0x590 fs/pipe.c:790
get_pipe_inode fs/pipe.c:881 [inline]
create_pipe_files+0x8d/0x880 fs/pipe.c:913
__do_pipe_flags fs/pipe.c:962 [inline]
do_pipe2+0x96/0x1b0 fs/pipe.c:1010
__do_sys_pipe2 fs/pipe.c:1028 [inline]
__se_sys_pipe2 fs/pipe.c:1026 [inline]
__x64_sys_pipe2+0x50/0x70 fs/pipe.c:1026
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+0x46/0xb0

Freed by task 5494:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x166/0x1c0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1754 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
slab_free mm/slub.c:3534 [inline]
kfree+0xe2/0x4d0 mm/slub.c:4562
put_pipe_info fs/pipe.c:711 [inline]
pipe_release+0x2b6/0x310 fs/pipe.c:734
__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:177
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xaf1/0x29f0 kernel/exit.c:795
do_group_exit+0xd2/0x2f0 kernel/exit.c:925
__do_sys_exit_group kernel/exit.c:936 [inline]
__se_sys_exit_group kernel/exit.c:934 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934
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+0x46/0xb0

The buggy address belongs to the object at ffff88807dc93000
which belongs to the cache kmalloc-cg-512 of size 512
The buggy address is located 360 bytes inside of
512-byte region [ffff88807dc93000, ffff88807dc93200)

The buggy address belongs to the physical page:
page:ffffea0001f72400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7dc90
head:ffffea0001f72400 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011842dc0
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5470, tgid 5470 (syz-executor105), ts 76271246150, free_ts 76264094282
prep_new_page mm/page_alloc.c:2535 [inline]
get_page_from_freelist+0x210d/0x3a30 mm/page_alloc.c:4282
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5506
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280
alloc_slab_page mm/slub.c:1824 [inline]
allocate_slab+0x27e/0x3d0 mm/slub.c:1969
new_slab mm/slub.c:2029 [inline]
___slab_alloc+0x89d/0xef0 mm/slub.c:3031
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
slab_alloc_node mm/slub.c:3209 [inline]
slab_alloc mm/slub.c:3251 [inline]
kmem_cache_alloc_trace+0x323/0x3e0 mm/slub.c:3282
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
alloc_pipe_info+0x105/0x590 fs/pipe.c:790
get_pipe_inode fs/pipe.c:881 [inline]
create_pipe_files+0x8d/0x880 fs/pipe.c:913
__do_pipe_flags fs/pipe.c:962 [inline]
do_pipe2+0x96/0x1b0 fs/pipe.c:1010
__do_sys_pipe2 fs/pipe.c:1028 [inline]
__se_sys_pipe2 fs/pipe.c:1026 [inline]
__x64_sys_pipe2+0x50/0x70 fs/pipe.c:1026
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+0x46/0xb0
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1453 [inline]
free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1503
free_unref_page_prepare mm/page_alloc.c:3383 [inline]
free_unref_page+0x19/0x4d0 mm/page_alloc.c:3479
__stack_depot_save+0x168/0x500 lib/stackdepot.c:489
kasan_save_stack+0x2e/0x40 mm/kasan/common.c:39
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:605 [inline]
kzalloc include/linux/slab.h:733 [inline]
kobject_get_path+0xbe/0x230 lib/kobject.c:147
kobject_uevent_env+0x254/0x1640 lib/kobject_uevent.c:529
call_crda+0x17e/0x3b0 net/wireless/reg.c:583
reg_query_database net/wireless/reg.c:1158 [inline]
reg_process_hint_core net/wireless/reg.c:2693 [inline]
reg_process_hint+0x925/0x1710 net/wireless/reg.c:3036
reg_process_pending_hints net/wireless/reg.c:3124 [inline]
reg_todo+0x1a5/0x7d0 net/wireless/reg.c:3212
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

Memory state around the buggy address:
ffff88807dc93000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807dc93080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807dc93100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807dc93180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807dc93200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

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