syzbot

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: 0 PID: 4455 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : btrfs_root_node+0xe0/0x3c8 fs/btrfs/ctree.c:150
lr : rcu_read_lock include/linux/rcupdate.h:792 [inline]
lr : btrfs_root_node+0x88/0x3c8 fs/btrfs/ctree.c:149
sp : ffff800020a07250
x29: ffff800020a07250 x28: dfff800000000000 x27: ffff800011eb51a0
x26: 0000000000000001 x25: ffff800011eb5920 x24: ffff800017a89000
x23: ffff800011eb5960 x22: ffff800017a89000 x21: 0000000000000001
x20: 0000000000000003 x19: 0000000000000018 x18: ffff800011abbcc0
x17: 1fffe00033ed797e x16: ffff8000082e8004 x15: ffff800008a20978
x14: ffff800008a1d7b4 x13: 1ffff00002a180b1 x12: 0000000000ff0100
x11: ff00800009ed973c x10: 0000000000000000 x9 : ffff800009ed973c
x8 : ffff0000e0b8d340 x7 : ffff800009eecc04 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002
x2 : 0000000000000008 x1 : ffff800011faa360 x0 : 0000000000000001
Call trace:
 rcu_read_lock include/linux/rcupdate.h:792 [inline]
 btrfs_root_node+0xe0/0x3c8 fs/btrfs/ctree.c:149
 btrfs_read_lock_root_node+0x6c/0x360 fs/btrfs/locking.c:277
 btrfs_build_ref_tree+0xe4/0xf74 fs/btrfs/ref-verify.c:995
 open_ctree+0x19b8/0x224c fs/btrfs/disk-io.c:3809
 btrfs_fill_super+0x1b4/0x2d4 fs/btrfs/super.c:1469
 btrfs_mount_root+0x730/0x780 fs/btrfs/super.c:1834
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632
 vfs_get_tree+0x90/0x274 fs/super.c:1573
 fc_mount fs/namespace.c:1039 [inline]
 vfs_kern_mount+0xdc/0x178 fs/namespace.c:1069
 btrfs_mount+0x2a0/0x8dc fs/btrfs/super.c:1894
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632
 vfs_get_tree+0x90/0x274 fs/super.c:1573
 do_new_mount+0x228/0x810 fs/namespace.c:3069
 path_mount+0x5b4/0xe78 fs/namespace.c:3399
 do_mount fs/namespace.c:3412 [inline]
 __do_sys_mount fs/namespace.c:3620 [inline]
 __se_sys_mount fs/namespace.c:3597 [inline]
 __arm64_sys_mount+0x49c/0x584 fs/namespace.c:3597
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 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:585
Code: 52806321 aa1703e2 392b42da 979012e9 (387c6a88) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	52806321 	mov	w1, #0x319                 	// #793
   4:	aa1703e2 	mov	x2, x23
   8:	392b42da 	strb	w26, [x22, #2768]
   c:	979012e9 	bl	0xfffffffffe404bb0
* 10:	387c6a88 	ldrb	w8, [x20, x28] <-- trapping instruction