==================================================================
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.5/21183

CPU: 0 PID: 21183 Comm: syz-executor.5 Not tainted 5.8.0-rc2-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:2012
 __block_write_begin fs/buffer.c:2062 [inline]
 block_write_begin+0x58/0x2e0 fs/buffer.c:2121
 minix_write_begin+0x35/0x220 fs/minix/inode.c:412
 generic_perform_write+0x20a/0x4f0 mm/filemap.c:3299
 __generic_file_write_iter+0x24b/0x610 mm/filemap.c:3428
 generic_file_write_iter+0x3a6/0x5c0 mm/filemap.c:3460
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x422/0x650 fs/read_write.c:484
 __vfs_write+0xc9/0x100 fs/read_write.c:497
 __kernel_write+0x11c/0x3a0 fs/read_write.c:516
 write_pipe_buf+0x153/0x1f0 fs/splice.c:799
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x3dc/0x830 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 default_file_splice_write fs/splice.c:811 [inline]
 do_splice_from fs/splice.c:847 [inline]
 do_splice+0x12a2/0x1820 fs/splice.c:1144
 __do_sys_splice fs/splice.c:1419 [inline]
 __se_sys_splice fs/splice.c:1401 [inline]
 __x64_sys_splice+0x198/0x250 fs/splice.c:1401
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb19
Code: Bad RIP value.
RSP: 002b:00007fe434351c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 0000000000509100 RCX: 000000000045cb19
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000078c040 R08: 0000000100000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000bec R14: 00000000004ceecd R15: 00007fe4343526d4
==================================================================