================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: null-ptr-deref in atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline] BUG: KASAN: null-ptr-deref in __refcount_sub_and_test include/linux/refcount.h:272 [inline] BUG: KASAN: null-ptr-deref in __refcount_dec_and_test include/linux/refcount.h:315 [inline] BUG: KASAN: null-ptr-deref in refcount_dec_and_test include/linux/refcount.h:333 [inline] BUG: KASAN: null-ptr-deref in kref_put include/linux/kref.h:64 [inline] BUG: KASAN: null-ptr-deref in bdi_put+0x22/0xa0 mm/backing-dev.c:901 Write of size 4 at addr 0000000000000040 by task syz-executor.1/10525 CPU: 0 PID: 10525 Comm: syz-executor.1 Not tainted 5.11.0-rc2-next-20210111-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 __kasan_report mm/kasan/report.c:400 [inline] kasan_report.cold+0x5f/0xd5 mm/kasan/report.c:413 check_memory_region_inline mm/kasan/generic.c:180 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:186 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline] __refcount_sub_and_test include/linux/refcount.h:272 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] kref_put include/linux/kref.h:64 [inline] bdi_put+0x22/0xa0 mm/backing-dev.c:901 bdev_evict_inode+0x262/0x460 fs/block_dev.c:808 evict+0x2ed/0x6b0 fs/inode.c:578 iput_final fs/inode.c:1654 [inline] iput.part.0+0x57e/0x810 fs/inode.c:1680 iput+0x58/0x70 fs/inode.c:1670 dentry_unlink_inode+0x2b1/0x3d0 fs/dcache.c:374 __dentry_kill+0x3c0/0x640 fs/dcache.c:579 dentry_kill fs/dcache.c:705 [inline] dput+0x725/0xbc0 fs/dcache.c:885 do_one_tree fs/dcache.c:1632 [inline] shrink_dcache_for_umount+0x11f/0x330 fs/dcache.c:1646 generic_shutdown_super+0x68/0x370 fs/super.c:447 kill_anon_super+0x36/0x60 fs/super.c:1055 deactivate_locked_super+0x94/0x160 fs/super.c:335 deactivate_super+0xad/0xd0 fs/super.c:366 put_fs_context+0xaa/0x650 fs/fs_context.c:442 fscontext_release+0x4c/0x60 fs/fsopen.c:73 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x417b71 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007fff88568770 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417b71 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000003 RBP: 0000000000000001 R08: 0000000000001ad2 R09: 00000000f3529ad6 R10: 00007fff88568850 R11: 0000000000000293 R12: ffffffffffffffff R13: 0000000000058c94 R14: 00000000000003e8 R15: 000000000119bf8c ==================================================================