MINIX-fs: mounting unchecked file system, running fsck is recommended
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BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:55 [inline]
BUG: KASAN: null-ptr-deref in trylock_buffer include/linux/buffer_head.h:359 [inline]
BUG: KASAN: null-ptr-deref in lock_buffer include/linux/buffer_head.h:365 [inline]
BUG: KASAN: null-ptr-deref in alloc_branch fs/minix/itree_common.c:88 [inline]
BUG: KASAN: null-ptr-deref in get_block+0x65c/0x13a0 fs/minix/itree_common.c:191
Write of size 8 at addr 0000000000000000 by task syz-executor.4/13285

CPU: 1 PID: 13285 Comm: syz-executor.4 Not tainted 5.8.0-rc3-next-20200703-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 __kasan_report mm/kasan/report.c:517 [inline]
 kasan_report.cold+0x5/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 instrument_atomic_write include/linux/instrumented.h:71 [inline]
 test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:55 [inline]
 trylock_buffer include/linux/buffer_head.h:359 [inline]
 lock_buffer include/linux/buffer_head.h:365 [inline]
 alloc_branch fs/minix/itree_common.c:88 [inline]
 get_block+0x65c/0x13a0 fs/minix/itree_common.c:191
 minix_get_block+0xe5/0x110 fs/minix/inode.c:376
 __block_write_begin_int+0x464/0x1a80 fs/buffer.c:2049
 __block_write_begin fs/buffer.c:2099 [inline]
 block_write_begin+0x58/0x2e0 fs/buffer.c:2158
 minix_write_begin+0x35/0x220 fs/minix/inode.c:412
 generic_perform_write+0x20a/0x4f0 mm/filemap.c:3344
 __generic_file_write_iter+0x24b/0x610 mm/filemap.c:3473
 generic_file_write_iter+0x3a6/0x5c0 mm/filemap.c:3505
 call_write_iter include/linux/fs.h:1877 [inline]
 new_sync_write+0x422/0x650 fs/read_write.c:484
 __vfs_write+0xc9/0x100 fs/read_write.c:497
 vfs_write+0x268/0x5d0 fs/read_write.c:559
 ksys_write+0x12d/0x250 fs/read_write.c:612
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:367
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb29
Code: Bad RIP value.
RSP: 002b:00007faf7f355c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000050d220 RCX: 000000000045cb29
RDX: 000000000000ff7f RSI: 0000000020000280 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000cee R14: 00000000004cf4f3 R15: 00007faf7f3566d4
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