syzbot


BUG: unable to handle kernel paging request in get_empty_nodes (2)

Status: upstream: reported C repro on 2026/05/03 07:32
Reported-by: syzbot+7b50dcfb9ae636c8b91e@syzkaller.appspotmail.com
First crash: 12d, last: 12d
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 BUG: unable to handle kernel paging request in get_empty_nodes 8 3 125d 131d 0/3 auto-obsoleted due to no activity on 2026/04/19 21:33
linux-6.6 KASAN: null-ptr-deref Read in get_empty_nodes 11 1 186d 186d 0/2 auto-obsoleted due to no activity on 2026/02/17 22:46

Sample crash report:
Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
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
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5441 Comm: syz.0.297 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline]
pc : set_buffer_journal_new fs/reiserfs/reiserfs.h:2834 [inline]
pc : get_empty_nodes+0x450/0x77c fs/reiserfs/fix_node.c:901
lr : sb_getblk include/linux/buffer_head.h:356 [inline]
lr : get_empty_nodes+0x448/0x77c fs/reiserfs/fix_node.c:890
sp : ffff800024a36820
x29: ffff800024a36960 x28: dfff800000000000 x27: ffff0000c5500000
x26: 0000000000000000 x25: 0000000000000000 x24: ffff800024a36910
x23: ffff0000df8f8018 x22: ffff0000df8f8160 x21: 1fffe0001bf1f003
x20: 1ffff00004946d97 x19: ffff800024a36910 x18: ffff800011b9bf60
x17: 1fffe00033eaa57e x16: ffff8000082eef80 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffff800065f4ce x12: 0000000000ff0100
x11: ff00800008a916bc x10: 0000000000000000 x9 : ffff800008a916bc
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800008a9148c
x2 : 0000000000000001 x1 : 0000000000000003 x0 : 0000000000000000
Call trace:
 sb_getblk include/linux/buffer_head.h:356 [inline]
 get_empty_nodes+0x450/0x77c fs/reiserfs/fix_node.c:890
 fix_nodes+0x1db0/0x6b70 fs/reiserfs/fix_node.c:2662
 reiserfs_paste_into_item+0x504/0x6e0 fs/reiserfs/stree.c:2130
 reiserfs_get_block+0x14a0/0x36e8 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x350/0x1388 fs/buffer.c:1991
 __block_write_begin+0x7c/0xa0 fs/buffer.c:2041
 reiserfs_write_begin+0x328/0x714 fs/reiserfs/inode.c:2775
 generic_cont_expand_simple+0x130/0x208 fs/buffer.c:2347
 reiserfs_setattr+0x51c/0xfec fs/reiserfs/inode.c:3305
 notify_change+0xb0c/0xdcc fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 vfs_truncate+0x23c/0x2b0 fs/open.c:111
 do_sys_truncate+0xec/0x1b4 fs/open.c:134
 __do_sys_truncate fs/open.c:146 [inline]
 __se_sys_truncate fs/open.c:144 [inline]
 __arm64_sys_truncate+0x5c/0x70 fs/open.c:144
 __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: 52800103 97f79ca7 d343fc08 aa0003fa (387c6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	52800103 	mov	w3, #0x8                   	// #8
   4:	97f79ca7 	bl	0xffffffffffde72a0
   8:	d343fc08 	lsr	x8, x0, #3
   c:	aa0003fa 	mov	x26, x0
* 10:	387c6908 	ldrb	w8, [x8, x28] <-- trapping instruction

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/03 11:04 linux-6.1.y 4931e0e1673d a0d91488 .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 get_empty_nodes
2026/05/03 09:51 linux-6.1.y 4931e0e1673d a0d91488 .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 get_empty_nodes
2026/05/03 07:32 linux-6.1.y 4931e0e1673d a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in get_empty_nodes
* Struck through repros no longer work on HEAD.