[syzbot] [block?] [bcachefs?] KASAN: slab-use-after-free Read in percpu_ref_put (2)

From: syzbot
Date: Thu Oct 10 2024 - 11:30:43 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 8f602276d390 Merge tag 'bcachefs-2024-10-05' of git://evil..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1033c7d0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ba92623fdea824c9
dashboard link: https://syzkaller.appspot.com/bug?extid=905d719acdbd213bf67e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1131f307980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15148327980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-8f602276.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d7abbd2b0653/vmlinux-8f602276.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6a9f3d168828/bzImage-8f602276.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/184260729fa9/mount_8.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+905d719acdbd213bf67e@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
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 ffff8880364920b0 by task kworker/u4:8/1067

CPU: 0 UID: 0 PID: 1067 Comm: kworker/u4:8 Not tainted 6.12.0-rc1-syzkaller-00349-g8f602276d390 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: loop0 loop_rootcg_workfn
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
blk_update_request+0x5e5/0x1160 block/blk-mq.c:923
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1051
loop_handle_cmd drivers/block/loop.c:1927 [inline]
loop_process_work+0x1c10/0x2170 drivers/block/loop.c:1945
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
worker_thread+0x870/0xd30 kernel/workqueue.c:3391
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 5114:
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:377 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:257 [inline]
__kmalloc_cache_noprof+0x19c/0x2c0 mm/slub.c:4295
kmalloc_noprof include/linux/slab.h:878 [inline]
kzalloc_noprof include/linux/slab.h:1014 [inline]
__bch2_dev_alloc+0x57/0xa60 fs/bcachefs/super.c:1289
bch2_dev_alloc+0xd4/0x170 fs/bcachefs/super.c:1359
bch2_fs_alloc fs/bcachefs/super.c:939 [inline]
bch2_fs_open+0x2e3f/0x2f80 fs/bcachefs/super.c:2050
bch2_fs_get_tree+0x738/0x1710 fs/bcachefs/fs.c:2067
vfs_get_tree+0x90/0x2b0 fs/super.c:1800
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4055 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4032
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 5114:
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 mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:2342 [inline]
slab_free mm/slub.c:4579 [inline]
kfree+0x1a0/0x440 mm/slub.c:4727
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:667
bch2_fs_get_tree+0xd9f/0x1710 fs/bcachefs/fs.c:2175
vfs_get_tree+0x90/0x2b0 fs/super.c:1800
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4055 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4032
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

The buggy address belongs to the object at ffff888036492000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 176 bytes inside of
freed 4096-byte region [ffff888036492000, ffff888036493000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36490
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801ac42140 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000001f5000000 0000000000000000
head: 04fff00000000040 ffff88801ac42140 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000001f5000000 0000000000000000
head: 04fff00000000003 ffffea0000d92401 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5114, tgid 5114 (syz-executor374), ts 95819092336, free_ts 95351745772
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1537
prep_new_page mm/page_alloc.c:1545 [inline]
get_page_from_freelist+0x3045/0x3190 mm/page_alloc.c:3457
__alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4733
alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
alloc_slab_page+0x6a/0x120 mm/slub.c:2412
allocate_slab+0x5a/0x2f0 mm/slub.c:2578
new_slab mm/slub.c:2631 [inline]
___slab_alloc+0xcd1/0x14b0 mm/slub.c:3818
__slab_alloc+0x58/0xa0 mm/slub.c:3908
__slab_alloc_node mm/slub.c:3961 [inline]
slab_alloc_node mm/slub.c:4122 [inline]
__do_kmalloc_node mm/slub.c:4263 [inline]
__kmalloc_noprof+0x25a/0x400 mm/slub.c:4276
mempool_init_node+0x1ee/0x4e0 mm/mempool.c:217
mempool_init_noprof+0x3a/0x50 mm/mempool.c:246
bch2_fs_btree_interior_update_init+0xca/0x100 fs/bcachefs/btree_update_interior.c:2706
bch2_fs_alloc fs/bcachefs/super.c:919 [inline]
bch2_fs_open+0x2af9/0x2f80 fs/bcachefs/super.c:2050
bch2_fs_get_tree+0x738/0x1710 fs/bcachefs/fs.c:2067
vfs_get_tree+0x90/0x2b0 fs/super.c:1800
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
page last free pid 5104 tgid 5104 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1108 [inline]
free_unref_page+0xcfb/0xf20 mm/page_alloc.c:2638
mempool_exit+0xc7/0x1a0 mm/mempool.c:170
bch2_fs_io_write_exit+0x19/0x40 fs/bcachefs/io_write.c:1673
__bch2_fs_free fs/bcachefs/super.c:550 [inline]
bch2_fs_release+0x1e1/0x7d0 fs/bcachefs/super.c:609
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_get_tree+0xd9f/0x1710 fs/bcachefs/fs.c:2175
vfs_get_tree+0x90/0x2b0 fs/super.c:1800
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4055 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4032
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:
ffff888036491f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888036492000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888036492080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888036492100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888036492180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Geert Uytterhoeven: "Re: [PATCH v3 12/12] arm64: defconfig: Enable Renesas RTCA-3 flag"
Previous message: Andy Shevchenko: "Re: [PATCH v8 7/8] platform/chrome: Introduce device tree hardware prober"
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