KASAN: invalid-free in hfsplus_bnode_free

Status: upstream: reported on 2026/09/13 22:12
Reported-by: syzbot+fbb9d71b385e63c87f4b@syzkaller.appspotmail.com
First crash: 15d, last: 15d

Sample crash report:
==================================================================
BUG: KASAN: double-free in slab_free mm/slub.c:3687 [inline]
BUG: KASAN: double-free in __kmem_cache_free+0xbc/0x21c mm/slub.c:3700
Free of addr ffff0000ca788000 by task syz.1.864/8516

CPU: 1 PID: 8516 Comm: syz.1.864 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report_invalid_free+0x98/0xe4 mm/kasan/report.c:489
 ____kasan_slab_free+0x168/0x1b0 mm/kasan/common.c:-1
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xbc/0x21c mm/slub.c:3700
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 hfsplus_bnode_free+0x288/0x2cc fs/hfsplus/bnode.c:619
 hfsplus_release_folio+0x384/0x48c fs/hfsplus/inode.c:103
 filemap_release_folio+0x174/0x24c mm/filemap.c:4026
 shrink_folio_list+0x1a58/0x4528 mm/vmscan.c:2003
 evict_folios+0x338c/0x4850 mm/vmscan.c:5053
 lru_gen_shrink_lruvec mm/vmscan.c:5236 [inline]
 shrink_lruvec+0x9fc/0x36a4 mm/vmscan.c:5931
 shrink_node_memcgs mm/vmscan.c:6152 [inline]
 shrink_node+0x4c0/0x20bc mm/vmscan.c:6183
 shrink_zones mm/vmscan.c:6424 [inline]
 do_try_to_free_pages+0x55c/0x1470 mm/vmscan.c:6486
 try_to_free_mem_cgroup_pages+0x2f4/0xa8c mm/vmscan.c:6801
 mem_cgroup_resize_max+0x250/0x2e4 mm/memcontrol.c:3506
 mem_cgroup_write+0x1f4/0x224 mm/memcontrol.c:-1
 cgroup_file_write+0x258/0x584 kernel/cgroup/cgroup.c:4101
 kernfs_fop_write_iter+0x390/0x4b4 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2271 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3c8/0x7c8 fs/read_write.c:584
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Allocated by task 8522:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc+0xd8/0x180 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 __hfs_bnode_create+0xd8/0x710 fs/hfsplus/bnode.c:468
 hfsplus_bnode_find+0x1f4/0xb44 fs/hfsplus/bnode.c:546
 hfsplus_brec_find+0x148/0x468 fs/hfsplus/bfind.c:178
 hfsplus_brec_read fs/hfsplus/bfind.c:217 [inline]
 hfsplus_brec_read_cat+0x38/0x334 fs/hfsplus/bfind.c:306
 hfsplus_find_cat+0x154/0x440 fs/hfsplus/catalog.c:202
 hfsplus_iget+0x40c/0x680 fs/hfsplus/super.c:101
 hfsplus_fill_super+0x9e0/0x1618 fs/hfsplus/super.c:522
 mount_bdev+0x264/0x35c fs/super.c:1454
 hfsplus_mount+0x44/0x58 fs/hfsplus/super.c:662
 legacy_get_tree+0xd8/0x174 fs/fs_context.c:632
 vfs_get_tree+0x90/0x278 fs/super.c:1584
 do_new_mount+0x228/0x804 fs/namespace.c:3078
 path_mount+0x5ac/0xe6c fs/namespace.c:3408
 do_mount fs/namespace.c:3421 [inline]
 __do_sys_mount fs/namespace.c:3629 [inline]
 __se_sys_mount fs/namespace.c:3606 [inline]
 __arm64_sys_mount+0x4a0/0x5a0 fs/namespace.c:3606
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Freed by task 8522:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xbc/0x21c mm/slub.c:3700
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 hfsplus_bnode_free+0x288/0x2cc fs/hfsplus/bnode.c:619
 hfsplus_btree_close+0xec/0x2a0 fs/hfsplus/btree.c:275
 hfsplus_put_super+0x1a4/0x300 fs/hfsplus/super.c:320
 generic_shutdown_super+0x138/0x32c fs/super.c:501
 kill_block_super+0x78/0xe0 fs/super.c:1481
 deactivate_locked_super+0xb4/0x128 fs/super.c:332
 deactivate_super+0xe4/0x104 fs/super.c:363
 cleanup_mnt+0x3a8/0x430 fs/namespace.c:1191
 __cleanup_mnt+0x20/0x30 fs/namespace.c:1198
 task_work_run+0x1f4/0x280 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 do_notify_resume+0x20f8/0x2c84 arch/arm64/kernel/signal.c:1151
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Last potentially related work creation:
 kasan_save_stack+0x40/0x70 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xc0/0xdc mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496
 call_rcu+0x104/0x958 kernel/rcu/tree.c:2849
 free_fib_info net/ipv4/fib_semantics.c:257 [inline]
 fib_info_put include/net/ip_fib.h:582 [inline]
 fib_release_info+0x558/0x674 net/ipv4/fib_semantics.c:283
 fib_table_flush+0x994/0xf08 net/ipv4/fib_trie.c:2077
 fib_flush net/ipv4/fib_frontend.c:195 [inline]
 fib_disable_ip+0xf8/0x174 net/ipv4/fib_frontend.c:1440
 fib_netdev_event+0x2f0/0x4a0 net/ipv4/fib_frontend.c:-1
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xd8/0x168 kernel/notifier.c:455
 call_netdevice_notifiers_info net/core/dev.c:2014 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
 call_netdevice_notifiers net/core/dev.c:2066 [inline]
 dev_close_many+0x2d4/0x448 net/core/dev.c:1614
 unregister_netdevice_many_notify+0x3f4/0x1900 net/core/dev.c:10997
 unregister_netdevice_many net/core/dev.c:11077 [inline]
 default_device_exit_batch+0x9d4/0xa70 net/core/dev.c:11549
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x650/0xa90 net/core/net_namespace.c:640
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

Second to last potentially related work creation:
 kasan_save_stack+0x40/0x70 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xc0/0xdc mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496
 kvfree_call_rcu+0xb4/0x6f0 kernel/rcu/tree.c:3405
 drop_sysctl_table+0x278/0x3c4 fs/proc/proc_sysctl.c:1731
 drop_sysctl_table+0x298/0x3c4 fs/proc/proc_sysctl.c:1734
 unregister_sysctl_table+0x90/0x134 fs/proc/proc_sysctl.c:1769
 unregister_net_sysctl_table+0x20/0x30 net/sysctl_net.c:174
 mpls_dev_sysctl_unregister net/mpls/af_mpls.c:1445 [inline]
 mpls_dev_notify+0x5f4/0x728 net/mpls/af_mpls.c:1665
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xd8/0x168 kernel/notifier.c:455
 call_netdevice_notifiers_info net/core/dev.c:2014 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
 call_netdevice_notifiers net/core/dev.c:2066 [inline]
 dev_change_name+0x5d4/0x86c net/core/dev.c:1295
 do_setlink+0x7e8/0x2158 net/core/rtnetlink.c:2825
 __rtnl_newlink net/core/rtnetlink.c:3622 [inline]
 rtnl_newlink+0x142c/0x1af0 net/core/rtnetlink.c:3669
 rtnetlink_rcv_msg+0x694/0xcc4 net/core/rtnetlink.c:6166
 netlink_rcv_skb+0x220/0x3ec net/netlink/af_netlink.c:2516
 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6184
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5fc/0x80c net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6f0/0x9d8 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x324/0x440 net/socket.c:2153
 __do_sys_sendto net/socket.c:2165 [inline]
 __se_sys_sendto net/socket.c:2161 [inline]
 __arm64_sys_sendto+0xe4/0x104 net/socket.c:2161
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the object at ffff0000ca788000
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes inside of
 256-byte region [ffff0000ca788000, ffff0000ca788100)

The buggy address belongs to the physical page:
page:000000009c511bc2 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10a788
head:000000009c511bc2 order:1 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 fffffc00033b1300 dead000000000006 ffff0000c0002480
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000ca787f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000ca787f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000ca788000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff0000ca788080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000ca788100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/13 22:12 linux-6.1.y cf82dcca9634 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: invalid-free in hfsplus_bnode_free
* Struck through repros no longer work on HEAD.