syzbot

FAT-fs (loop0): utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
FAT-fs (loop0): Invalid FSINFO signature: 0x41615252, 0x80417272 (sector = 1)
Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5257 Comm: syz.0.349 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 42400405 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : fat_ioctl_filldir+0x28c/0xdf4 fs/fat/dir.c:759
lr : fat_ioctl_filldir+0x268/0xdf4 fs/fat/dir.c:759
sp : ffff80001ff57970
x29: ffff80001ff579a0 x28: dfff800000000000 x27: 00000000200010aa
x26: 1ffff00003feaf8b x25: 1fffe0001b0c96d4 x24: ffff800011439ae0
x23: 00000000fffffff2 x22: ffff0000d864b6a4 x21: ffff0000d864b680
x20: 000000200010aa00 x19: ffff80001ff57c58 x18: 0000000000000000
x17: ffff800016d04000 x16: ffff800008e3dc94 x15: ffff8000167e4500
x14: ffff0000d864c080 x13: dfff800000000000 x12: 0000000000ff0100
x11: 0000000000000000 x10: 00000000200010aa x9 : 0000ffffffffffff
x8 : 00000000200010aa x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff800016fb2c50 x4 : 0000000000000008 x3 : ffff8000082bfb8c
x2 : 0000000000000001 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
 fat_ioctl_filldir+0x28c/0xdf4 fs/fat/dir.c:759
 dir_emit_dot include/linux/fs.h:3717 [inline]
 dir_emit_dots include/linux/fs.h:3728 [inline]
 __fat_readdir+0x24c/0x132c fs/fat/dir.c:576
 fat_ioctl_readdir fs/fat/dir.c:777 [inline]
 fat_dir_ioctl+0x280/0x36c fs/fat/dir.c:815
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: d503229f 2a1f03f7 2a1f03e0 38000957 (2a1703e1) 
---[ end trace 2ac9048cbfd32c4b ]---
----------------
Code disassembly (best guess):
   0:	d503229f 	csdb
   4:	2a1f03f7 	mov	w23, wzr
   8:	2a1f03e0 	mov	w0, wzr
   c:	38000957 	sttrb	w23, [x10]
* 10:	2a1703e1 	mov	w1, w23 <-- trapping instruction