__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589
Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5035 Comm: syz.1.133 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026
pstate: 02400005 (nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : ext4_mb_get_buddy_page_lock fs/ext4/mballoc.c:1380 [inline]
pc : ext4_mb_init_group+0x14c/0x614 fs/ext4/mballoc.c:1440
lr : ext4_mb_get_buddy_page_lock fs/ext4/mballoc.c:1376 [inline]
lr : ext4_mb_init_group+0xf8/0x614 fs/ext4/mballoc.c:1440
sp : ffff800022957000
x29: ffff800022957020 x28: 0000000000000018 x27: 0000000000000002
x26: 0000000000000000 x25: 0000000000000800 x24: ffff0000f68f2b00
x23: 0000000000000000 x22: ffff0000e1974000 x21: 1fffe000198b4403
x20: ffff0000cc5a2018 x19: 0000000000000000 x18: 1fffe00033c2177e
x17: 0000000000000000 x16: ffff8000082de324 x15: 0000000000000002
x14: 0000000000000001 x13: 1ffff00002cd02ea x12: 0000000000080000
x11: 0000000000024368 x10: ffff800023029000 x9 : dfff800000000000
x8 : 0000000000000003 x7 : 00000000000e46b8 x6 : 00000000000e4670
x5 : ffff8000229563f8 x4 : ffff8000164b2e80 x3 : ffff80000aa9f758
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
dump_backtrace(regs = 000000007266658e tsk = 0000000000000000)
Call trace:
 ext4_mb_get_buddy_page_lock fs/ext4/mballoc.c:1380 [inline]
 ext4_mb_init_group+0x14c/0x614 fs/ext4/mballoc.c:1440
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2584 [inline]
 ext4_mb_regular_allocator+0xcf8/0x2b60 fs/ext4/mballoc.c:2791
 ext4_mb_new_blocks+0xb78/0x4244 fs/ext4/mballoc.c:5793
 ext4_ext_map_blocks+0x12bc/0x5680 fs/ext4/extents.c:4369
 ext4_map_blocks+0x7b0/0x160c fs/ext4/inode.c:681
 ext4_getblk+0x178/0x680 fs/ext4/inode.c:892
 ext4_bread+0x3c/0x1a8 fs/ext4/inode.c:948
 ext4_append+0x23c/0x488 fs/ext4/namei.c:83
 ext4_init_new_dir+0x270/0x4f0 fs/ext4/namei.c:3032
 ext4_mkdir+0x3b8/0xa28 fs/ext4/namei.c:3078
 vfs_mkdir+0x314/0x4d8 fs/namei.c:4161
 do_mkdirat+0x1b8/0x3ec fs/namei.c:4186
 __do_sys_mkdirat fs/namei.c:4201 [inline]
 __se_sys_mkdirat fs/namei.c:4199 [inline]
 __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4199
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589
Code: 9100627c d2d00009 d343ff88 f2fbffe9 (38696908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	9100627c 	add	x28, x19, #0x18
   4:	d2d00009 	mov	x9, #0x800000000000        	// #140737488355328
   8:	d343ff88 	lsr	x8, x28, #3
   c:	f2fbffe9 	movk	x9, #0xdfff, lsl #48
* 10:	38696908 	ldrb	w8, [x8, x9] <-- trapping instruction