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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+0x657/0x1380 fs/minix/itree_common.c:191
Write of size 8 at addr 0000000000000000 by task syz-executor.2/8629

CPU: 0 PID: 8629 Comm: syz-executor.2 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 __kasan_report.cold+0x5/0x4d mm/kasan/report.c:515
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 check_memory_region_inline mm/kasan/generic.c:187 [inline]
 check_memory_region+0x141/0x190 mm/kasan/generic.c:193
 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+0x657/0x1380 fs/minix/itree_common.c:191
 minix_get_block+0xe5/0x110 fs/minix/inode.c:376
 __block_write_begin_int+0x490/0x1b00 fs/buffer.c:2002
 __block_write_begin fs/buffer.c:2052 [inline]
 block_write_begin+0x58/0x2e0 fs/buffer.c:2111
 minix_write_begin+0x35/0xe0 fs/minix/inode.c:412
 generic_perform_write+0x20a/0x4e0 mm/filemap.c:3302
 __generic_file_write_iter+0x24c/0x610 mm/filemap.c:3431
 generic_file_write_iter+0x3f3/0x630 mm/filemap.c:3463
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x4a2/0x700 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_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
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