[syzbot] [bcachefs?] KASAN: slab-use-after-free Read in percpu_ref_put

[syzbot <syzbot+9e0404b505e604f67e41@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    0b58e108042b Add linux-next specific files for 20240703
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=178e9bae980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ed034204f2e40e53
dashboard link: https://syzkaller.appspot.com/bug?extid=9e0404b505e604f67e41
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d079762feae/disk-0b58e108.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e53996c8d8c2/vmlinux-0b58e108.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a0bf21cdd844/bzImage-0b58e108.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9e0404b505e604f67e41@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in __ref_is_percpu include/linux/percpu-refcount.h:174 [inline]
BUG: KASAN: slab-use-after-free in percpu_ref_put_many include/linux/percpu-refcount.h:332 [inline]
BUG: KASAN: slab-use-after-free in percpu_ref_put+0xda/0x250 include/linux/percpu-refcount.h:351
Read of size 8 at addr ffff888041f600b0 by task kworker/1:5/5142

CPU: 1 UID: 0 PID: 5142 Comm: kworker/1:5 Not tainted 6.10.0-rc6-next-20240703-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: bcachefs_write_ref bch2_do_discards_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 __ref_is_percpu include/linux/percpu-refcount.h:174 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:332 [inline]
 percpu_ref_put+0xda/0x250 include/linux/percpu-refcount.h:351
 bch2_do_discards_work+0x286a/0x2d10 fs/bcachefs/alloc_background.c:1871
 process_one_work kernel/workqueue.c:3224 [inline]
 process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3305
 worker_thread+0x86d/0xd40 kernel/workqueue.c:3383
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 11370:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __kmalloc_cache_noprof+0x19c/0x2c0 mm/slub.c:4189
 kmalloc_noprof include/linux/slab.h:680 [inline]
 kzalloc_noprof include/linux/slab.h:806 [inline]
 __bch2_dev_alloc+0x57/0xa60 fs/bcachefs/super.c:1286
 bch2_dev_alloc+0xd4/0x170 fs/bcachefs/super.c:1356
 bch2_fs_alloc+0x1f70/0x20a0 fs/bcachefs/super.c:935
 bch2_fs_open+0x8cc/0xdf0 fs/bcachefs/super.c:2113
 bch2_fs_get_tree+0x750/0x16c0 fs/bcachefs/fs.c:1925
 vfs_get_tree+0x90/0x2a0 fs/super.c:1789
 do_new_mount+0x2be/0xb40 fs/namespace.c:3471
 do_mount fs/namespace.c:3811 [inline]
 __do_sys_mount fs/namespace.c:4019 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3996
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 11370:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2231 [inline]
 slab_free mm/slub.c:4473 [inline]
 kfree+0x149/0x360 mm/slub.c:4594
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22f/0x480 lib/kobject.c:737
 bch2_fs_free+0x27b/0x3c0 fs/bcachefs/super.c:663
 bch2_fs_get_tree+0xf6f/0x16c0 fs/bcachefs/fs.c:2031
 vfs_get_tree+0x90/0x2a0 fs/super.c:1789
 do_new_mount+0x2be/0xb40 fs/namespace.c:3471
 do_mount fs/namespace.c:3811 [inline]
 __do_sys_mount fs/namespace.c:4019 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3996
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
 insert_work+0x3e/0x330 kernel/workqueue.c:2182
 __queue_work+0xc16/0xee0 kernel/workqueue.c:2334
 queue_work_on+0x1c2/0x380 kernel/workqueue.c:2385
 queue_work include/linux/workqueue.h:621 [inline]
 bch2_dev_do_discards+0x189/0x200 fs/bcachefs/alloc_background.c:1884
 bch2_do_discards+0x29/0x60 fs/bcachefs/alloc_background.c:1895
 journal_write_done+0x785/0xea0 fs/bcachefs/journal_io.c:1631
 process_one_work kernel/workqueue.c:3224 [inline]
 process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3305
 worker_thread+0x86d/0xd40 kernel/workqueue.c:3383
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Second to last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
 insert_work+0x3e/0x330 kernel/workqueue.c:2182
 __queue_work+0xc16/0xee0 kernel/workqueue.c:2334
 queue_work_on+0x1c2/0x380 kernel/workqueue.c:2385
 queue_work include/linux/workqueue.h:621 [inline]
 bch2_dev_do_discards+0x189/0x200 fs/bcachefs/alloc_background.c:1884
 bch2_do_discards+0x29/0x60 fs/bcachefs/alloc_background.c:1895
 journal_write_done+0x785/0xea0 fs/bcachefs/journal_io.c:1631
 process_one_work kernel/workqueue.c:3224 [inline]
 process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3305
 worker_thread+0x86d/0xd40 kernel/workqueue.c:3383
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff888041f60000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 176 bytes inside of
 freed 4096-byte region [ffff888041f60000, ffff888041f61000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x41f60
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 00fff00000000040 ffff888015042140 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000040004 00000001fdffffff 0000000000000000
head: 00fff00000000040 ffff888015042140 0000000000000000 dead000000000001
head: 0000000000000000 0000000000040004 00000001fdffffff 0000000000000000
head: 00fff00000000003 ffffea000107d801 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5767, tgid 5767 (dhcpcd), ts 127655970402, free_ts 127602728804
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x2ccb/0x2d80 mm/page_alloc.c:3480
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4738
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x5f/0x120 mm/slub.c:2300
 allocate_slab+0x5a/0x2f0 mm/slub.c:2463
 new_slab mm/slub.c:2516 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3702
 __slab_alloc+0x58/0xa0 mm/slub.c:3792
 __slab_alloc_node mm/slub.c:3845 [inline]
 slab_alloc_node mm/slub.c:4025 [inline]
 __do_kmalloc_node mm/slub.c:4157 [inline]
 __kmalloc_noprof+0x25a/0x400 mm/slub.c:4170
 kmalloc_noprof include/linux/slab.h:684 [inline]
 tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
 tomoyo_realpath_nofollow+0xba/0x100 security/tomoyo/realpath.c:304
 tomoyo_find_next_domain+0x272/0x1cf0 security/tomoyo/domain.c:727
 tomoyo_bprm_check_security+0x115/0x180 security/tomoyo/tomoyo.c:102
 security_bprm_check+0x65/0x90 security/security.c:1194
 search_binary_handler fs/exec.c:1787 [inline]
 exec_binprm fs/exec.c:1841 [inline]
 bprm_execve+0xa56/0x1770 fs/exec.c:1892
 do_execveat_common+0x553/0x700 fs/exec.c:1999
 do_execve fs/exec.c:2073 [inline]
 __do_sys_execve fs/exec.c:2149 [inline]
 __se_sys_execve fs/exec.c:2144 [inline]
 __x64_sys_execve+0x92/0xb0 fs/exec.c:2144
page last free pid 5763 tgid 5763 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2644
 __slab_free+0x31b/0x3d0 mm/slub.c:4384
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3975 [inline]
 slab_alloc_node mm/slub.c:4037 [inline]
 __do_kmalloc_node mm/slub.c:4157 [inline]
 __kmalloc_noprof+0x1a6/0x400 mm/slub.c:4170
 kmalloc_noprof include/linux/slab.h:684 [inline]
 kzalloc_noprof include/linux/slab.h:806 [inline]
 lsm_task_alloc security/security.c:694 [inline]
 security_task_alloc+0x43/0x130 security/security.c:3041
 copy_process+0x1692/0x3d90 kernel/fork.c:2358
 kernel_clone+0x226/0x8f0 kernel/fork.c:2788
 __do_sys_clone3 kernel/fork.c:3089 [inline]
 __se_sys_clone3+0x2cb/0x350 kernel/fork.c:3073
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888041f5ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888041f60000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888041f60080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff888041f60100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888041f60180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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