syzbot


BUG: unable to handle kernel paging request in balance_internal

Status: upstream: reported C repro on 2026/03/30 03:10
Reported-by: syzbot+7a24548bcd165232f4c1@syzkaller.appspotmail.com
First crash: 3d07h, last: 3d04h
Bug presence (1)
Date Name Commit Repro Result
2026/03/30 upstream (ToT) 7aaa8047eafd C Failed due to an error; will retry later

Sample crash report:
REISERFS warning (device loop0): vs-13060 reiserfs_update_sd_size: stat data of object [2 2 0x0 SD] (nlink == 1) not found (pos 0)
REISERFS warning (device loop0): vs-13060 reiserfs_update_sd_size: stat data of object [2 2 0x0 SD] (nlink == 1) not found (pos 0)
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: 4495 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/26/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : balance_internal_when_delete fs/reiserfs/ibalance.c:675 [inline]
pc : balance_internal+0x2238/0x3ee8 fs/reiserfs/ibalance.c:849
lr : balance_internal_when_delete fs/reiserfs/ibalance.c:668 [inline]
lr : balance_internal+0x2210/0x3ee8 fs/reiserfs/ibalance.c:849
sp : ffff8000210b6940
x29: ffff8000210b6b80 x28: ffff700004216d48 x27: dfff800000000000
x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000001
x23: 0000000000000000 x22: 0000000000000018 x21: 0000000000000000
x20: ffff8000210b6da0 x19: ffff0000e0af4828 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000082d1110 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe0001c15e905 x12: 0000000000ff0100
x11: ff00800008ccbcb8 x10: 0000000000000000 x9 : ffff800008ccbcb8
x8 : 0000000000000003 x7 : 49ce0fe700000213 x6 : 49ce0fe700000213
x5 : ffff0000de851020 x4 : ffff0000de851030 x3 : ffff800008cea2b0
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 balance_internal_when_delete fs/reiserfs/ibalance.c:675 [inline]
 balance_internal+0x2238/0x3ee8 fs/reiserfs/ibalance.c:849
 do_balance+0x2b0/0x790 fs/reiserfs/do_balan.c:1896
 reiserfs_delete_solid_item+0x750/0xca4 fs/reiserfs/stree.c:1462
 remove_save_link+0x1e4/0x350 fs/reiserfs/super.c:540
 reiserfs_truncate_file+0x6c0/0xb00 fs/reiserfs/inode.c:2322
 reiserfs_setattr+0xab4/0xfec fs/reiserfs/inode.c:3395
 notify_change+0xb0c/0xdcc fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 handle_truncate fs/namei.c:3293 [inline]
 do_open fs/namei.c:3638 [inline]
 path_openat+0x2110/0x26bc fs/namei.c:3791
 do_filp_open+0x194/0x384 fs/namei.c:3818
 do_sys_openat2+0x134/0x3f4 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __arm64_sys_openat+0x118/0x14c fs/open.c:1347
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 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: 97f06e0a f94002b5 910062b6 d343fec8 (387b6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	97f06e0a 	bl	0xffffffffffc1b828
   4:	f94002b5 	ldr	x21, [x21]
   8:	910062b6 	add	x22, x21, #0x18
   c:	d343fec8 	lsr	x8, x22, #3
* 10:	387b6908 	ldrb	w8, [x8, x27] <-- trapping instruction

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/30 05:42 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in balance_internal
2026/03/30 04:49 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in balance_internal
2026/03/30 04:01 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in balance_internal
2026/03/30 03:09 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in balance_internal
* Struck through repros no longer work on HEAD.