loop3: rw=0, want=6434, limit=52
attempt to access beyond end of device
loop3: rw=2049, want=6434, limit=52
attempt to access beyond end of device
loop3: rw=2049, want=6436, limit=52
BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: test_and_set_bit arch/x86/include/asm/bitops.h:220 [inline]
IP: test_and_set_bit_lock arch/x86/include/asm/bitops.h:234 [inline]
IP: trylock_buffer include/linux/buffer_head.h:367 [inline]
IP: lock_buffer include/linux/buffer_head.h:373 [inline]
IP: alloc_branch fs/minix/itree_common.c:88 [inline]
IP: get_block+0x6a3/0x1100 fs/minix/itree_common.c:191
PGD 5725e067 P4D 5725e067 PUD a99a5067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 5249 Comm: syz-executor.0 Not tainted 4.14.183-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808f6ca600 task.stack: ffff888053c28000
RIP: 0010:test_and_set_bit arch/x86/include/asm/bitops.h:220 [inline]
RIP: 0010:test_and_set_bit_lock arch/x86/include/asm/bitops.h:234 [inline]
RIP: 0010:trylock_buffer include/linux/buffer_head.h:367 [inline]
RIP: 0010:lock_buffer include/linux/buffer_head.h:373 [inline]
RIP: 0010:alloc_branch fs/minix/itree_common.c:88 [inline]
RIP: 0010:get_block+0x6a3/0x1100 fs/minix/itree_common.c:191
RSP: 0018:ffff888053c2f348 EFLAGS: 00010246
RAX: 0000000000000007 RBX: ffff888053c2f450 RCX: 1ffffffff0fe7914
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffff88808f6ca624
RBP: ffff888053c2f4c8 R08: 0000000000000001 R09: 0000000000000002
R10: ffff88808f6caed8 R11: ffff88808f6ca600 R12: ffff888055831240
R13: ffff888053c2f414 R14: dffffc0000000000 R15: 0000000000000000
FS:  00007fb25d654700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000051762000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 minix_get_block+0xd6/0x100 fs/minix/inode.c:379
 __block_write_begin_int+0x33a/0x1000 fs/buffer.c:2038
 __block_write_begin fs/buffer.c:2088 [inline]
 block_write_begin+0x58/0x260 fs/buffer.c:2147
 minix_write_begin+0x35/0xc0 fs/minix/inode.c:415
 generic_perform_write+0x1c9/0x420 mm/filemap.c:3047
 __generic_file_write_iter+0x227/0x590 mm/filemap.c:3172
 generic_file_write_iter+0x36f/0x650 mm/filemap.c:3200
 call_write_iter include/linux/fs.h:1778 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x44e/0x630 fs/read_write.c:482
 __kernel_write+0xf5/0x330 fs/read_write.c:501
 write_pipe_buf+0x143/0x1b0 fs/splice.c:797
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x332/0x740 fs/splice.c:626
 splice_from_pipe+0xc6/0x120 fs/splice.c:661
 default_file_splice_write+0x37/0x80 fs/splice.c:809
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x115/0x160 fs/splice.c:1018
 splice_direct_to_actor+0x27e/0x730 fs/splice.c:973
 do_splice_direct+0x164/0x210 fs/splice.c:1061
 do_sendfile+0x469/0xaf0 fs/read_write.c:1441
 SYSC_sendfile64 fs/read_write.c:1496 [inline]
 SyS_sendfile64+0x9b/0x110 fs/read_write.c:1488
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45ca69
RSP: 002b:00007fb25d653c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004fc580 RCX: 000000000045ca69
RDX: 00000000200001c0 RSI: 0000000000000003 RDI: 0000000000000003
RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008dc R14: 00000000004cba56 R15: 00007fb25d6546d4
Code: ef 08 00 00 49 8b bf 28 01 00 00 b9 08 00 00 00 e8 13 57 c6 ff 31 d2 be 74 01 00 00 48 c7 c7 e0 e7 99 86 49 89 c7 e8 6d 28 6d ff <f0> 49 0f ba 2f 02 0f 83 1e fe ff ff e8 cc c8 89 ff 4c 89 ff e8 
RIP: test_and_set_bit arch/x86/include/asm/bitops.h:220 [inline] RSP: ffff888053c2f348
RIP: test_and_set_bit_lock arch/x86/include/asm/bitops.h:234 [inline] RSP: ffff888053c2f348
RIP: trylock_buffer include/linux/buffer_head.h:367 [inline] RSP: ffff888053c2f348
RIP: lock_buffer include/linux/buffer_head.h:373 [inline] RSP: ffff888053c2f348
RIP: alloc_branch fs/minix/itree_common.c:88 [inline] RSP: ffff888053c2f348
RIP: get_block+0x6a3/0x1100 fs/minix/itree_common.c:191 RSP: ffff888053c2f348
CR2: 0000000000000000
minix_free_inode: bit 1 already cleared
---[ end trace 0c9beae23d22bddf ]---