================================================================== 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+0xd0/0x360 include/linux/percpu-refcount.h:351 Read of size 8 at addr ffff0000ea6460b0 by task kworker/0:5/6351 CPU: 0 PID: 6351 Comm: kworker/0:5 Not tainted 6.10.0-rc7-syzkaller-gc912bf709078 #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: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0x198/0x538 mm/kasan/report.c:488 kasan_report+0xd8/0x138 mm/kasan/report.c:601 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 __ref_is_percpu include/linux/percpu-refcount.h:174 [inline] percpu_ref_put_many include/linux/percpu-refcount.h:332 [inline] percpu_ref_put+0xd0/0x360 include/linux/percpu-refcount.h:351 bch2_do_discards_work+0x180c/0x1b78 fs/bcachefs/alloc_background.c:1824 process_one_work+0x79c/0x15b8 kernel/workqueue.c:3248 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Allocated by task 7503: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:565 poison_kmalloc_redzone mm/kasan/common.c:370 [inline] __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:387 kasan_kmalloc include/linux/kasan.h:211 [inline] kmalloc_trace_noprof+0x244/0x374 mm/slub.c:4154 kmalloc_noprof include/linux/slab.h:660 [inline] kzalloc_noprof include/linux/slab.h:778 [inline] __bch2_dev_alloc+0x6c/0x844 fs/bcachefs/super.c:1288 bch2_dev_alloc+0xc4/0x154 fs/bcachefs/super.c:1358 bch2_fs_alloc+0x1b98/0x1c94 fs/bcachefs/super.c:936 bch2_fs_open+0x740/0xb64 fs/bcachefs/super.c:2111 bch2_mount+0x4fc/0xe68 fs/bcachefs/fs.c:1926 legacy_get_tree+0xd4/0x16c fs/fs_context.c:662 vfs_get_tree+0x90/0x288 fs/super.c:1789 do_new_mount+0x278/0x900 fs/namespace.c:3352 path_mount+0x590/0xe04 fs/namespace.c:3679 do_mount fs/namespace.c:3692 [inline] __do_sys_mount fs/namespace.c:3898 [inline] __se_sys_mount fs/namespace.c:3875 [inline] __arm64_sys_mount+0x3c4/0x488 fs/namespace.c:3875 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:131 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:150 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598 Freed by task 6611: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_free_info+0x54/0x6c mm/kasan/generic.c:579 poison_slab_object+0x128/0x180 mm/kasan/common.c:240 __kasan_slab_free+0x3c/0x70 mm/kasan/common.c:256 kasan_slab_free include/linux/kasan.h:184 [inline] slab_free_hook mm/slub.c:2196 [inline] slab_free mm/slub.c:4438 [inline] kfree+0x154/0x3e0 mm/slub.c:4559 bch2_dev_release+0x20/0x30 fs/bcachefs/super.c:1181 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2a8/0x41c lib/kobject.c:737 bch2_dev_free+0x174/0x1bc fs/bcachefs/super.c:1211 bch2_fs_free+0x208/0x334 fs/bcachefs/super.c:662 bch2_kill_sb+0x48/0x58 fs/bcachefs/fs.c:2045 deactivate_locked_super+0xc4/0x12c fs/super.c:473 deactivate_super+0xe0/0x100 fs/super.c:506 cleanup_mnt+0x34c/0x3dc fs/namespace.c:1267 __cleanup_mnt+0x20/0x30 fs/namespace.c:1274 task_work_run+0x230/0x2e0 kernel/task_work.c:180 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] do_notify_resume+0x178/0x1f4 arch/arm64/kernel/entry-common.c:151 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline] el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:713 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598 Last potentially related work creation: kasan_save_stack+0x40/0x6c mm/kasan/common.c:47 __kasan_record_aux_stack+0xd0/0xec mm/kasan/generic.c:541 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:551 insert_work+0x54/0x2d4 kernel/workqueue.c:2208 __queue_work+0xdc4/0x12ac kernel/workqueue.c:2360 queue_work_on+0xe0/0x1a0 kernel/workqueue.c:2411 queue_work include/linux/workqueue.h:621 [inline] bch2_dev_do_discards+0x148/0x1b8 fs/bcachefs/alloc_background.c:1837 bch2_do_discards+0x34/0x6c fs/bcachefs/alloc_background.c:1848 journal_write_done+0x5a0/0xb4c fs/bcachefs/journal_io.c:1628 process_one_work+0x79c/0x15b8 kernel/workqueue.c:3248 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Second to last potentially related work creation: kasan_save_stack+0x40/0x6c mm/kasan/common.c:47 __kasan_record_aux_stack+0xd0/0xec mm/kasan/generic.c:541 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:551 insert_work+0x54/0x2d4 kernel/workqueue.c:2208 __queue_work+0xdc4/0x12ac kernel/workqueue.c:2360 queue_work_on+0xe0/0x1a0 kernel/workqueue.c:2411 queue_work include/linux/workqueue.h:621 [inline] bch2_dev_do_discards+0x148/0x1b8 fs/bcachefs/alloc_background.c:1837 bch2_do_discards+0x34/0x6c fs/bcachefs/alloc_background.c:1848 journal_write_done+0x5a0/0xb4c fs/bcachefs/journal_io.c:1628 process_one_work+0x79c/0x15b8 kernel/workqueue.c:3248 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 The buggy address belongs to the object at ffff0000ea646000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 176 bytes inside of freed 4096-byte region [ffff0000ea646000, ffff0000ea647000) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12a640 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff) page_type: 0xffffefff(slab) raw: 05ffc00000000040 ffff0000c0002140 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000040004 00000001ffffefff 0000000000000000 head: 05ffc00000000040 ffff0000c0002140 dead000000000122 0000000000000000 head: 0000000000000000 0000000000040004 00000001ffffefff 0000000000000000 head: 05ffc00000000003 fffffdffc3a99001 ffffffffffffffff 0000000000000000 head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000ea645f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000ea646000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff0000ea646080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000ea646100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000ea646180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Mem abort info: ESR = 0x0000000096000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x06: level 2 translation fault Data abort info: ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=00000001186ab000 [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 6351 Comm: kworker/0:5 Tainted: G B 6.10.0-rc7-syzkaller-gc912bf709078 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Workqueue: bcachefs_write_ref bch2_do_discards_work pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __lse_atomic64_fetch_add arch/arm64/include/asm/atomic_lse.h:169 [inline] pc : __lse_atomic64_fetch_sub arch/arm64/include/asm/atomic_lse.h:184 [inline] pc : __lse_atomic64_sub_return arch/arm64/include/asm/atomic_lse.h:204 [inline] pc : arch_atomic64_sub_return arch/arm64/include/asm/atomic.h:92 [inline] pc : raw_atomic64_sub_return include/linux/atomic/atomic-arch-fallback.h:2913 [inline] pc : raw_atomic64_sub_and_test include/linux/atomic/atomic-arch-fallback.h:4386 [inline] pc : raw_atomic_long_sub_and_test include/linux/atomic/atomic-long.h:1551 [inline] pc : atomic_long_sub_and_test include/linux/atomic/atomic-instrumented.h:4522 [inline] pc : percpu_ref_put_many include/linux/percpu-refcount.h:334 [inline] pc : percpu_ref_put+0x268/0x360 include/linux/percpu-refcount.h:351 lr : arch_atomic64_sub_return arch/arm64/include/asm/atomic.h:92 [inline] lr : raw_atomic64_sub_return include/linux/atomic/atomic-arch-fallback.h:2913 [inline] lr : raw_atomic64_sub_and_test include/linux/atomic/atomic-arch-fallback.h:4386 [inline] lr : raw_atomic_long_sub_and_test include/linux/atomic/atomic-long.h:1551 [inline] lr : atomic_long_sub_and_test include/linux/atomic/atomic-instrumented.h:4522 [inline] lr : percpu_ref_put_many include/linux/percpu-refcount.h:334 [inline] lr : percpu_ref_put+0x264/0x360 include/linux/percpu-refcount.h:351 sp : ffff8000997e7660 x29: ffff8000997e7660 x28: 0000000000000000 x27: 0000000000000000 x26: ffff8000997e79c0 x25: dfff800000000000 x24: ffff8000997e7980 x23: 1fffe0001d4c8c17 x22: dfff800000000000 x21: 0000000000000000 x20: ffff0000ea6460b8 x19: ffff0000ea6460b0 x18: 1fffe000367ac9de x17: ffff80008f0fd000 x16: ffff80008afc4f4c x15: 0000000000000001 x14: 1ffff0001249d09c x13: 0000000000000000 x12: 0000000000000000 x11: ffff70001249d09d x10: 0000000000ff0100 x9 : 0000000000000000 x8 : ffffffffffffffff x7 : 1fffe000367ac9df x6 : ffff8000802a3bb0 x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000826835c8 x2 : 0000000000000001 x1 : 0000000000000008 x0 : 0000000000000001 Call trace: arch_atomic64_sub_return arch/arm64/include/asm/atomic.h:92 [inline] raw_atomic64_sub_return include/linux/atomic/atomic-arch-fallback.h:2913 [inline] raw_atomic64_sub_and_test include/linux/atomic/atomic-arch-fallback.h:4386 [inline] raw_atomic_long_sub_and_test include/linux/atomic/atomic-long.h:1551 [inline] atomic_long_sub_and_test include/linux/atomic/atomic-instrumented.h:4522 [inline] percpu_ref_put_many include/linux/percpu-refcount.h:334 [inline] percpu_ref_put+0x268/0x360 include/linux/percpu-refcount.h:351 bch2_do_discards_work+0x180c/0x1b78 fs/bcachefs/alloc_background.c:1824 process_one_work+0x79c/0x15b8 kernel/workqueue.c:3248 process_scheduled_works kernel/workqueue.c:3329 [inline] worker_thread+0x938/0xecc kernel/workqueue.c:3409 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Code: 978f2adc d503201f 977b2207 92800008 (f8e802a8) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: 978f2adc bl 0xfffffffffe3cab70 4: d503201f nop 8: 977b2207 bl 0xfffffffffdec8824 c: 92800008 mov x8, #0xffffffffffffffff // #-1 * 10: f8e802a8 ldaddal x8, x8, [x21] <-- trapping instruction