syzbot


BUG: unable to handle kernel paging request in get_empty_nodes

Status: upstream: reported on 2026/01/03 23:10
Reported-by: syzbot+09ac93a00a6b946e9505@syzkaller.appspotmail.com
First crash: 16d, last: 10d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: null-ptr-deref Read in get_empty_nodes 11 1 71d 71d 0/2 upstream: reported on 2025/11/09 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: 5830 Comm: syz.5.491 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
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+0x424/0x750 fs/reiserfs/fix_node.c:901
lr : sb_getblk include/linux/buffer_head.h:356 [inline]
lr : get_empty_nodes+0x41c/0x750 fs/reiserfs/fix_node.c:890
sp : ffff8000219a6e20
x29: ffff8000219a6f60 x28: dfff800000000000 x27: ffff0000c058ee00
x26: 0000000000000000 x25: 0000000000000000 x24: ffff8000219a6f10
x23: ffff000101462018 x22: ffff000101462160 x21: 1fffe0002028c403
x20: 1ffff00004334e53 x19: ffff8000219a6f10 x18: ffff800011a5bd40
x17: ffff800018184000 x16: ffff8000082e9244 x15: ffff8000089caab0
x14: ffff8000089ca7f4 x13: 1ffff00002a0a0b1 x12: 0000000000080000
x11: 000000000001aab1 x10: ffff80002ba18000 x9 : ffff800008a80900
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000008 x3 : ffff800008a806c8
x2 : 0000000000000001 x1 : 0000000000000003 x0 : 0000000000000000
Call trace:
 sb_getblk include/linux/buffer_head.h:356 [inline]
 get_empty_nodes+0x424/0x750 fs/reiserfs/fix_node.c:890
 fix_nodes+0x1dd8/0x6b4c fs/reiserfs/fix_node.c:2662
 reiserfs_insert_item+0x7d8/0x9f4 fs/reiserfs/stree.c:2240
 reiserfs_new_directory+0x400/0x6e8 fs/reiserfs/inode.c:1846
 reiserfs_new_inode+0xc64/0x133c fs/reiserfs/inode.c:2068
 reiserfs_mkdir+0x4a8/0x788 fs/reiserfs/namei.c:845
 vfs_mkdir+0x314/0x4d4 fs/namei.c:4114
 do_mkdirat+0x1b4/0x3e0 fs/namei.c:4139
 __do_sys_mkdirat fs/namei.c:4154 [inline]
 __se_sys_mkdirat fs/namei.c:4152 [inline]
 __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4152
 __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: 52800103 97f7ad6d d343fc08 aa0003fa (387c6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	52800103 	mov	w3, #0x8                   	// #8
   4:	97f7ad6d 	bl	0xffffffffffdeb5b8
   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
2026/01/09 21:32 linux-6.1.y 50cbba13faa2 d6526ea3 .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
2026/01/09 21:24 linux-6.1.y 50cbba13faa2 d6526ea3 .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
2026/01/03 23:10 linux-6.1.y 50cbba13faa2 d6526ea3 .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.