------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 3231 at lib/refcount.c:87 refcount_dec_and_lock+0x180/0x1ec lib/refcount.c:146 Modules linked in: CPU: 0 PID: 3231 Comm: syz-executor.4 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022 pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : refcount_dec_and_lock+0x180/0x1ec lib/refcount.c:146 lr : refcount_dec_not_one lib/refcount.c:87 [inline] lr : refcount_dec_and_lock+0x17c/0x1ec lib/refcount.c:146 sp : ffff80001270bb20 x29: ffff80001270bb20 x28: ffff80000cc15062 x27: ffff00012cde4a40 x26: 0000000000000002 x25: 00000000ffffffff x24: 0000000000000000 x23: 00000000c0000000 x22: 0000000000000000 x21: ffff80000d5eb4a0 x20: ffff00010321fd20 x19: ffff80000d8c8000 x18: 00000000000000c0 x17: ffff80000dd0b198 x16: ffff80000db49158 x15: ffff000110bf8000 x14: 0000000000000000 x13: 00000000ffffffff x12: ffff000110bf8000 x11: ff808000081c0d5c x10: 0000000000000000 x9 : e97c00d734432000 x8 : e97c00d734432000 x7 : ffff80000819545c x6 : 0000000000000000 x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000100000000 x0 : 0000000000000000 Call trace: refcount_dec_and_lock+0x180/0x1ec lib/refcount.c:146 nilfs_put_root+0x30/0x80 fs/nilfs2/the_nilfs.c:797 nilfs_segctor_destroy fs/nilfs2/segment.c:2747 [inline] nilfs_detach_log_writer+0x3b8/0x4d0 fs/nilfs2/segment.c:2810 nilfs_put_super+0x28/0x9c fs/nilfs2/super.c:468 generic_shutdown_super+0x8c/0x190 fs/super.c:491 kill_block_super+0x30/0x78 fs/super.c:1427 deactivate_locked_super+0x70/0xe8 fs/super.c:332 deactivate_super+0xd0/0xd4 fs/super.c:363 cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186 __cleanup_mnt+0x20/0x30 fs/namespace.c:1193 task_work_run+0xc4/0x14c kernel/task_work.c:177 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127 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+0x9c/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 irq event stamp: 3313244 hardirqs last enabled at (3313243): [<ffff8000081befc8>] __up_console_sem+0xb0/0xfc kernel/printk/printk.c:264 hardirqs last disabled at (3313244): [<ffff80000bfb5fbc>] el1_dbg+0x24/0x5c arch/arm64/kernel/entry-common.c:404 softirqs last enabled at (3312600): [<ffff80000801c33c>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 softirqs last disabled at (3312598): [<ffff80000801c308>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19 ---[ end trace 0000000000000000 ]--- Unable to handle kernel paging request at virtual address fffffffffffffeb8 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000001c566b000 [fffffffffffffeb8] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 3231 Comm: syz-executor.4 Tainted: G W 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : nilfs_mdt_fetch_dirty+0x1c/0x94 fs/nilfs2/mdt.c:394 lr : nilfs_mdt_fetch_dirty+0x18/0x94 fs/nilfs2/mdt.c:391 sp : ffff80001270bb00 x29: ffff80001270bb00 x28: ffff80000cc15062 x27: ffff000121983e40 x26: 0000000000000002 x25: ffff000121983c48 x24: ffff00011aab4a30 x23: 0000000000000002 x22: ffff000121983c00 x21: ffff00011aab4800 x20: ffff00010321fd00 x19: 0000000000000000 x18: 00000000000001be x17: ffff80000bffd6bc x16: ffff80000db49158 x15: ffff000110bf8000 x14: 0000000000000000 x13: 00000000ffffffff x12: ffff000110bf8000 x11: ff80800008f55b48 x10: 0000000000000000 x9 : ffff800008f55b48 x8 : fffffffffffffeb8 x7 : ffff80000813754c x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002 x2 : 0000000000000008 x1 : ffff00010321fd00 x0 : 0000000000000000 Call trace: nilfs_mdt_fetch_dirty+0x1c/0x94 fs/nilfs2/mdt.c:394 nilfs_test_metadata_dirty+0x2c/0x148 fs/nilfs2/segment.c:813 nilfs_segctor_confirm+0x30/0x1a8 fs/nilfs2/segment.c:837 nilfs_segctor_destroy fs/nilfs2/segment.c:2729 [inline] nilfs_detach_log_writer+0x1f0/0x4d0 fs/nilfs2/segment.c:2810 nilfs_put_super+0x28/0x9c fs/nilfs2/super.c:468 generic_shutdown_super+0x8c/0x190 fs/super.c:491 kill_block_super+0x30/0x78 fs/super.c:1427 deactivate_locked_super+0x70/0xe8 fs/super.c:332 deactivate_super+0xd0/0xd4 fs/super.c:363 cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186 __cleanup_mnt+0x20/0x30 fs/namespace.c:1193 task_work_run+0xc4/0x14c kernel/task_work.c:177 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127 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+0x9c/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 Code: 910003fd aa0003f3 97cd2834 d1052268 (f9400100) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: 910003fd mov x29, sp 4: aa0003f3 mov x19, x0 8: 97cd2834 bl 0xffffffffff34a0d8 c: d1052268 sub x8, x19, #0x148 * 10: f9400100 ldr x0, [x8] <-- trapping instruction