loop0: detected capacity change from 0 to 16
=====================================================
BUG: KMSAN: uninit-value in cont_expand_zero fs/buffer.c:2428 [inline]
BUG: KMSAN: uninit-value in cont_write_begin+0xd84/0xdc0 fs/buffer.c:2453
 cont_expand_zero fs/buffer.c:2428 [inline]
 cont_write_begin+0xd84/0xdc0 fs/buffer.c:2453
 fat_write_begin+0x92/0x260 fs/fat/inode.c:235
 generic_perform_write+0x3f5/0xc00 mm/filemap.c:3787
 __generic_file_write_iter+0x38f/0x910 mm/filemap.c:3915
 generic_file_write_iter+0xfc/0x430 mm/filemap.c:3947
 do_iter_readv_writev+0x65c/0x7e0
 do_iter_write+0x35d/0xe00 fs/read_write.c:852
 vfs_iter_write+0x84/0xe0 fs/read_write.c:893
 iter_file_splice_write+0xce6/0x17e0 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x12c/0x1e0 fs/splice.c:936
 splice_direct_to_actor+0x8b5/0x11a0 fs/splice.c:891
 do_splice_direct+0x252/0x3d0 fs/splice.c:979
 generic_copy_file_range fs/read_write.c:1379 [inline]
 do_copy_file_range fs/read_write.c:1402 [inline]
 vfs_copy_file_range+0x141d/0x2530 fs/read_write.c:1509
 __do_sys_copy_file_range fs/read_write.c:1562 [inline]
 __se_sys_copy_file_range+0x47a/0x9f0 fs/read_write.c:1529
 __ia32_sys_copy_file_range+0x115/0x190 fs/read_write.c:1529
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x95/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Local variable fsdata.i created at:
 cont_write_begin+0xc1/0xdc0 fs/buffer.c:2453
 fat_write_begin+0x92/0x260 fs/fat/inode.c:235

CPU: 1 PID: 4160 Comm: syz-executor.0 Not tainted 5.18.0-syzkaller-16263-g2d0ce79ea812 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================