sysv_free_block: trying to free block not in datazone
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BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:57 [inline]
BUG: KASAN: null-ptr-deref in trylock_buffer include/linux/buffer_head.h:399 [inline]
BUG: KASAN: null-ptr-deref in lock_buffer include/linux/buffer_head.h:405 [inline]
BUG: KASAN: null-ptr-deref in alloc_branch fs/sysv/itree.c:148 [inline]
BUG: KASAN: null-ptr-deref in get_block+0x567/0x16a0 fs/sysv/itree.c:251
Write of size 8 at addr 0000000000000000 by task syz-executor.4/5359

CPU: 1 PID: 5359 Comm: syz-executor.4 Not tainted 6.4.0-rc2-syzkaller-00018-g4d6d4c7f541d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_report+0xe6/0x540 mm/kasan/report.c:465
 kasan_report+0x176/0x1b0 mm/kasan/report.c:572
 kasan_check_range+0x283/0x290 mm/kasan/generic.c:187
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:57 [inline]
 trylock_buffer include/linux/buffer_head.h:399 [inline]
 lock_buffer include/linux/buffer_head.h:405 [inline]
 alloc_branch fs/sysv/itree.c:148 [inline]
 get_block+0x567/0x16a0 fs/sysv/itree.c:251
 __block_write_begin_int+0x548/0x1a50 fs/buffer.c:2064
 __block_write_begin fs/buffer.c:2114 [inline]
 block_write_begin+0x9c/0x1f0 fs/buffer.c:2175
 sysv_write_begin+0x31/0x70 fs/sysv/itree.c:485
 generic_perform_write+0x300/0x5e0 mm/filemap.c:3923
 __generic_file_write_iter+0x17a/0x400 mm/filemap.c:4051
 generic_file_write_iter+0xaf/0x310 mm/filemap.c:4083
 do_iter_write+0x7b1/0xcb0 fs/read_write.c:860
 vfs_writev fs/read_write.c:933 [inline]
 do_pwritev+0x21a/0x360 fs/read_write.c:1030
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f2bc528c169
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2bc5f37168 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
RAX: ffffffffffffffda RBX: 00007f2bc53abf80 RCX: 00007f2bc528c169
RDX: 0000000000000005 RSI: 0000000020000480 RDI: 0000000000000004
RBP: 00007f2bc52e7ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc3ef3e80f R14: 00007f2bc5f37300 R15: 0000000000022000
 </TASK>
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